So, here’s my annual spring buyer’s guide to desktop PCs. Most of what I say below also applies to laptops, although with laptops there are additional factors, such as size, weight, screen size and battery life. As always, these tips apply to mainstream users doing typical tasks, not hard-core gamers or techies.

Last fall, I advised average consumers with aging PCs to hang on until new Vista PCs emerged, rather than trying to upgrade existing models. I still believe that was the right course, because Windows upgrades are so tricky. But it turns out that even new Vista PCs have two big downsides.

First, Vista isn’t all that exciting a replacement for Windows XP. It’s much prettier and has much better searching, and Microsoft claims it has much stronger security, although you still need add-on security software.

Second, to an extent that amazes me, makers of Windows software and hardware have failed to update their products to work smoothly, or to work at all, with Vista. In my house, for example, the only built-in Vista printer driver I can find for my printer doesn’t allow the two-sided printing I can do with Windows XP and Apple Macintosh computers.

So, if you desperately need a new Windows PC, be prepared to be underwhelmed and to be frustrated by incompatible software and hardware. And if you’re not desperate, you might wait another six months or so for the software and hardware to catch up — and for Microsoft to issue some bug fixes.

Or you could buy a Mac instead. I still believe the best desktop computer on the market for mainstream, nontechnical consumers is the Apple iMac. It has gorgeous hardware and superior built-in software. Its operating system, Mac OS X, includes most of the key new features of Vista. And the iMac can even run Vista, along with its own operating system, if you need the occasional Windows program.

Apple has delayed until October the release of its new operating-system version, Leopard. But it’s almost certain that any Mac you buy now will upgrade to it smoothly. (See my Mossberg’s Mailbox for more details.) And the Mac is still largely free of the security problems that add such hassles to using a Windows PC.

But if you’re going for a Windows PC, here are my buying tips.

Vista Versions: The cheapest PCs will have only a stripped-down edition of Vista called Home Basic, which lacks Vista’s flashy new user interface. To get the full Vista experience, you’ll need more expensive machines that come with Home Premium, which also has more media features and is probably best for most average consumers.

If your company recommends it, you may need a different version of Vista called Vista Business, which lacks some of the media features, but can connect to some types of company networks that the Home versions can’t. Or you can buy a machine with the costliest version of Vista, called Ultimate, that includes all the features of the other versions. If you want to shun Vista altogether, you may still be able to find new PCs with Windows XP, though these machines may not be as secure as Vista models.

Memory: No matter what Microsoft or the PC makers say, I strongly suggest one gigabyte of memory, or RAM, for Home Basic, and two gigabytes for all other Vista versions.

Video: Vista Home Premium, Business and Ultimate will work best on machines with a separate, or “discrete,” graphics card with dedicated video memory. Some integrated graphics systems — built into the computer’s main circuitry — will also work, though they will drain some of your main memory through a scheme called shared memory.

Processor: For Home Basic, any current Intel or AMD processor in a new brand-name PC will work. For other versions, I suggest a “dual core” processor, like Intel’s Core 2 Duo, or AMD’s Athlon 64 X2, which pack the equivalent of two chips into one. Even if your processor can handle so-called 64-bit software, average users won’t find that capability useful today.

Hard drive: If you’re not much interested in video, music or photos, 80 or 100 gigabytes should be sufficient. If you are, 250 gigabytes or more is best.

Disks: Don’t buy one of the competing new high-definition disk drives, Blu-ray or HD-DVD, until the war between these competing formats is settled. Stick with plain old DVD.

Junky software: Nearly all Windows PCs are packed with “craplets” — the useless, annoying trial versions of programs. In a retail store, they may remove these for you for a small fee.

Price: You can get a bargain, brand-name desktop with Home Basic and a slow processor for under $400. But for a versatile desktop with two gigabytes of memory, discrete video, a large hard disk and a dual-core processor, you can easily spend $800 or more, without a monitor.

Just don’t buy more, or less, machine than you need.

Email me at mossberg@wsj.com.

Partisans of these platforms can argue all day about which is better. But the competitors have some things in common. Windows computers and Apple Macintoshes can both display the same photos and office documents, and play the same MP3 songs and YouTube videos. BlackBerrys and Treos can receive the same emails and call the same phone numbers.

It isn’t perfect. There are some files that don’t play well across platforms. But most common content does.

Yet there’s another technology competition that doesn’t share content well and offers few, if any, benefits to consumers. It’s the fight among two groups of technology companies and movie studios to sell a successor to the DVD. Each has developed a new type of disc that has the ability to show movies in high definition. To my eye, the pictures they deliver are identical.

Neither of these competing new discs, called Blu-ray and HD-DVD, works in current DVD players. They require very expensive new players, and the new players can’t handle both new disc formats, only one or the other.

Adding to the annoyance: Some movie studios release movies only in one of the two formats. Paramount and Warner Brothers support both formats, but Universal supports only HD-DVD, and Disney, Fox and Sony only Blu-ray.

So, in order to be sure you can play any movie released as a high-definition disc, you would have to replace your old DVD player with two new, much costlier players. It would be like having to buy separate TV sets to watch different networks’ programs.

Now, however, one gutsy company, LG Electronics, of Korea, a longtime member of the Blu-ray camp, has broken ranks and introduced a new combo player that can handle three formats: Blu-ray, HD-DVD, and regular old DVDs. It’s called the BH100 Super Multi Blue.

I’ve tested this combo player and found that it plays both new formats, as well as regular DVDs, just fine. But it’s more expensive than most single-format players and has some serious limitations when navigating through the menus on HD-DVD titles. For now, I can only recommend it for serious videophiles with deep pockets, but I’m hoping it’s the start of a trend that will end the foolish war.

The BH100 costs $1,200. That’s vastly more expensive than the newest DVD players, which, for less than $100, can take a regular DVD and “upscale” it so it looks better on a high-definition set. But that $1,200 isn’t so outrageous if you compare it with the price of buying two separate Blu-ray and HD-DVD players, which can reach or exceed $1,000 total. And the new LG takes up only one input on your TV, occupies less space on your component shelf and requires just one remote control.

I tested the LG combo player on my high-definition TV with this year’s Oscar-winning best picture, “The Departed,” and with “Superman Returns,” each of which is available in both of the new formats, as well as on DVD.

All played perfectly. The picture looked great in both formats and was noticeably better than an upscaled DVD image, which the LG unit also can produce. The LG outputs both new formats in a high, but grossly overhyped, resolution called “1080p.”

But the BH100 did a much better job with the Blu-ray discs than with the HD-DVD titles. That’s because while the combo player can play HD-DVD movies perfectly, it can’t display the HD-DVD discs’ menus for selecting scenes or accessing special features.

These menus usually offer the title and a photo to identify a scene, and the title and/or a description of the special feature. But on the LG BH100, the HD-DVD menus have no pictures, titles, or descriptions and look nothing like the original. They only identify scenes by number and duration. That makes it hard to find, say, the deleted scenes from “The Departed,” or the documentaries on the Superman disc.

The BH100 was based on a Blu-ray-only player and lacks the special chips HD-DVD players use to display the menus properly. LG had to concoct its own rudimentary replacements for those menus. The company says a future combo model could include the chips and thus display the HD-DVD menus as well as it does the Blu-ray menus, but it hasn’t decided whether to make such a product.

One reason for that decision may be the competing approach to solving the stupid disc war. Warner Brothers is working on a combo disc, instead of a combo player. This disc would hold both the Blu-ray and HD-DVD versions of a movie, so you could pop it into whichever type of player you own.

Until the electronics and movie companies support universal high-definition players and/or universal high-definition discs, I don’t recommend that most people invest in either technology. Why prolong a war that’s bad for consumers?

Email me at mossberg@wsj.com. See video versions of my reviews at wsj.com/mossbergvideo.