Computerworld tested the final version of SP1, and we found some improvements and a potential holdup

The final version of Vista SP1 focuses on under-the-hood improvements to reliability, security and performance, with very few changes made to the interface or Vista's features. Think of it as a giant, glorified set of patches and fixes rather than a clear and visible change to the operating system.

Although Vista Service Pack 1 won't be available to the general public until sometime in March, I received a copy of the final code and put it through its paces. My verdict? Don't expect many surprises from SP1 -- think of it as a big, glorified set of fixes and patches rolled into one.

As a review of a beta version of SP1, the service pack leaves just about all of the operating system's features intact and targets performance, reliability and security. One fix -- the death of the so-called Kill Switch -- will be welcomed by many.

One of the biggest benefits Microsoft touts for Vista SP1 is faster performance, notably the speed with which it copies files to local disks and across networks. But on some test machine, copying to local disks and across networks with Vista SP1 is generally slightly slower than pre-SP1 and lags far behind Windows XP.

It's not clear whether my results will bear out when compared to many machines. Microsoft says, in fact, that its internal testing shows speed improvements of up to 50% when copying files. So be aware that what you get on your machine may be dramatically different from what I found on mine, or what Microsoft found on its machine.
Installation

Installation of SP1 was straightforward and took a little over an hour. The PC rebooted multiple times and required no action on my part. At various points during installation, you'll be told that you're at Stage 1, Stage 2 or Stage 3 of a three-stage process, and you'll be told the percentage of that stage that still remains. In my installation, however, I found that I was given misleading information. For example, after I was told Stage 3 was complete, I got a message telling me that Stage 3 was 0% complete. Still, given that you don't need to take any action on them, these misleading messages are no more than minor irritants.

Hands-on Vista SP1: Better but slower? Sp1_overview_sm

One more minor irritant may happen when the installation is complete and you log in. You may be greeted, as I was, by a warning that there are "Multiple Security Problems with your Computer," even though I had no such problems before the SP1 install. Click the Security Center icon, and you'll be able to find out the source of the security problems. In my case, SP1 had shut off Windows Defender and User Account Control (no great loss, of course). From the Security Center, you can turn Windows Defender and User Account Control back on, if you'd like.

Hands-on Vista SP1: Better but slower? Sp1_security_center_sm

Right after installation, you may notice that your PC appears more sluggish than it had previously. That's because when you install SP1, all your SuperFetch data, which is used to speed up your PC, is cleared from your system. Over time, though, as you use SP1, your system will speed up as it begins to regather SuperFetch data.