Of course, one feature IT shops weren't expecting – a 10 percent performance advantage over SP2 – managed to slip in as well. And while the performance boost measured by an independent testing entity (see my blog entry "XP Widening the Gap vs. Vista") may be nothing more than the accumulated impact of all those post-SP2 Hotfix tweaks, it certainly doesn't hurt and helps make the case for sticking with Windows XP that much stronger.

Verdict: Windows XP Service Pack 3 is a must-have update for IT shops seeking to extend the life of Windows XP.

Windows Vista Service Pack 1
Service Pack 1 for Windows Vista was a disappointment long before the final bits were frozen. Preliminary tests of a Release Candidate build – and later confirmed against the RTM code – showed that SP1 would do nothing to address the myriad performance issues that Vista's early adopters warned us about. Those areas that it did address (file copy operations between local and/or network volumes), while important, were highly specific and had no impact on the general sluggishness and poor overall application throughput that frustrates users to this day.

Recognizing that SP1 is not, and never will be, a performance silver bullet, IT shops are now trying to take stock of what the Service Pack does offer. As with XP Service Pack 3, there are no real headliners. The kernel has been upgraded to the same revision level as Windows Server 2008 (including the built-in backdoor for anti-virus vendors). BitLocker now supports more drive types and configuration scenarios. There are the usual bug fixes and compatibility tweaks. Windows Update has many more drivers available for a better out-of-box experience. Battery life should improve for certain classes of notebook PCs.

Overall, Vista SP1 is an unimpressive release (view table of highlights). In fact, the whole SP1 experience seems a bit anticlimactic. After a year of hush-hush denials and a general refusal to discuss anything Service Pack related, Microsoft's finished effort seems, well, unfinished. Redmond still has huge performance issues to resolve, even on state-of-the-art hardware. More mysteriously, Microsoft's own server team has churned out a version of Windows – using the same kernel and core SP1 bits -- that clobbers Vista across a range of benchmark tests.

Verdict: Deploy Windows Vista Service Pack 1 for the Hotfix consolidation value. You might also get a much-needed driver in the bargain; just don't expect much in the way of performance improvements.