About 18 months ago, the giant PC maker brought out an unusual desktop computer called the TouchSmart, a bulky model meant for kitchen counters. It was intended as a walk-up home kiosk, with large icons you could activate by merely touching them to check the weather or to consult your calendar.

This TouchSmart was praised for its originality, but it wasn’t as practical as promised, and wasn’t a big hit. Still, H-P is persevering with the concept. It has refined the hardware and the touch-controlled software, and has come up with a new line set to go on sale by mid-July.

This new TouchSmart, which comes in two models priced at $1,299 and $1,499, is a relatively slim, one-piece desktop with a large 22-inch screen. It resembles the Apple iMac or the Dell XPS One and, like the latter, runs Microsoft’s Windows Vista. It has a wireless keyboard and mouse, and can be used as a normal Vista computer.

But, like the first TouchSmart, this new model comes with H-P’s touch-controlled user interface and special programs designed to be manipulated with your fingers. For this model, H-P is de-emphasizing the idea that the machine is meant for the kitchen, but it is forging ahead strongly with the notion that touch control is the wave of the future.

After testing the new TouchSmart PC for a few days, my verdict is mixed. The TouchSmart software is indeed improved. It’s attractive, more versatile and more practical — and fun to use. The hardware is handsome and well-equipped. And H-P deserves credit for continuing to build software expertise in a world where makers of computers and cellphones must become as expert at software as they are at hardware. But the latest effort has some problems.

The TouchSmart interface is inviting. There’s a top row with huge icons, called tiles, displaying your favorite programs, and a bottom row of smaller tiles for other programs. You can scroll each row with a finger and decide which programs go in which row. You can even include in either row not only TouchSmart programs, but the regular Windows programs or Web sites that you like. When you tap on a tile that isn’t for a special TouchSmart program, the computer pops you into the regular Windows interface. To return to the TouchSmart interface, you just tap a home button below the screen.

Hewlett-Packard’s TouchSmart

The TouchSmart software includes a calendar, a weather widget, a clock, music and video players, a program for composing short notes, and even a basic Web browser. All worked OK in my tests, but they’re simple and limited.

The computer itself is fairly powerful. Both models have dual-core processors, large hard disks, and a whopping 4 gigabytes of memory. And both run the special 64-bit version of Vista, which allows more memory usage and can be much faster than regular Vista, but only if you buy special 64-bit software programs. This machine is loaded with every conceivable port and connector, mostly hidden from view, and the high-end model even has a TV tuner.

But this is still a Vista computer, with all of the disadvantages that entails, especially a sluggish start-up and an annoying barrage of pop-up warnings. And the new TouchSmart is preloaded with craplets, those irritating trial programs and come-ons that you didn’t order.

There’s a built-in Webcam that works in low light, but it’s almost impossible to tilt the computer forward to get the best shot. Plus, the TouchSmart software interface is very basic and is ragged around the edges. It isn’t a multitouch interface — like the ones on the Apple iPhone and in the next version of Windows, code-named Windows 7, that recognize a variety of gestures and perform different tasks when multiple fingers are used rather than just one. For example, you can’t rotate a photo on the TouchSmart by grabbing it with your fingers, or move back and forth through Web pages by swiping the browser with your fingers.

The TouchSmart software is just a thin shell plopped on top of Vista, and it crashed on me four times during the course of a few days of testing. Also, the limitations of the TouchSmart applications can be frustrating. The photo application wouldn’t let me create albums. The music application didn’t display artist names for some of my MP3 files, and the calendar application can’t display an onscreen reminder of an event if you’re working in the main Vista interface.

If you’re intrigued by the idea of a quick and simple interface on a handsome one-piece Vista machine, the TouchSmart might make sense. But it doesn’t deliver on the full promise of touch computing.

• Find all of Walt Mossberg’s columns and videos online, free, at the new All Things Digital Web site, http://walt.allthingsd.com. Email him at mossberg@wsj.com.

The arrival of a large update like this isn’t a sign of trouble, or even unusual. Microsoft has routinely issued these large “service packs” periodically for Windows. And just this week, its competitor, Apple, unleashed an even larger update for its new operating system, Leopard.

Even though they can take a long time to download and install, such updates are generally a good thing for consumers. Microsoft will automatically deliver SP1, as the company calls it, through its normal updating mechanism, built into Windows. The update is free.

However, based on my tests of Vista SP1, I believe that for most average consumers, it will likely be a nonevent, and for others it will be disappointing. Many of its benefits are aimed at corporations and power users, or are under-the-hood fixes that are hard to discern. For mainstream users, it adds no significant, visible features to Vista, and changes little or nothing about the way the operating system looks and works.

Also, SP1 doesn’t resolve some of the most annoying flaws in Vista, including slow start-ups and reboots, and a security system that nags you too much and requires add-on anti-virus software. I guess these problems will either never be fixed fully or will have to wait for SP2.

While Vista SP1 does deliver some performance improvements in certain scenarios, it can actually temporarily degrade performance — including making reboots even slower — because of a quirk in the update process. This slowdown should go away in a few days, the company says.

On balance, the update is probably worth installing, especially since Microsoft will deliver it automatically. But I wouldn’t rush to grab it and I wouldn’t expect much from it. One note: you can’t install SP1 until you have installed a couple of other patches first. These will also be distributed automatically.

I installed Vista SP1 on two computers that had come with the original Vista preinstalled: a 10-month-old Sony Vaio SZ laptop and a two-month-old Dell XPS One desktop. Because the automatic download distribution isn’t yet in place, Microsoft sent me the update on a disk, which also included the prerequisite patches. In each case, the upgrade took a little over an hour and went smoothly. During the process, the computers rebooted multiple times, but it was all automatic and didn’t require user intervention.

After the installation, the computers functioned normally. I tested three of the performance improvements Microsoft claims for SP1. The first involved speeding up the copying of hefty folders containing large numbers of files. On both machines, copying a folder containing over 700 files totaling almost 700 megabytes took less than half as long with SP1 as it had with the original Vista.

I also tested how long it took both machines to awaken from a hibernation or sleep state and be ready for work. For these tests, I began with each machine running Microsoft Word, Microsoft Outlook and the Firefox Web browser, then I forced them into sleep and hibernation mode.

By my definition, “ready for work” means that Vista’s circular delay indicator has gone away, the software that loads at start-up has finished launching and the computer has fully reconnected to its wired or wireless network. On both of my test machines, SP1 improved the recovery time from sleep or hibernation, shaving one to 10 seconds from the procedures.

Microsoft doesn’t claim SP1 will improve the speed of cold starts and reboots under Vista, but I tested these anyway. To my horror, I found that SP1 actually made rebooting — already slower than on comparable Windows XP computers or Macintoshes — even slower.

Microsoft explained that this was due to the fact that installing SP1 erases certain data used by Vista to speed up program launching. It takes the system a few days to build this data back up, the company says. Until then, it says, overall performance, including reboots, can be slower under SP1 than under original Vista.

Microsoft provided me with a method that would rebuild this program-launching data more quickly, at least for the common programs I was using in my tests. Once I followed that method, rebooting time returned to its former state — still too slow for my taste, but at least not worse.

In briefing me on SP1, Microsoft made a big point of saying that great progress had been made in the past year in making Vista work properly with add-on devices, such as printers. I tried my 2003-vintage Hewlett-Packard printer, which hadn’t worked properly with the original Vista. It still didn’t work well with SP1.

So, Vista SP1 is a step forward, at least after a few days of use. But it’s not a big step.

Email me at mossberg@wsj.com. Find all my columns and videos online, free, at the new All Things Digital Web site, http://walt.allthingsd.com.