Hey Steve,
I agree with you on stability, but based on my desktop experience with Windows XP, Linux, and OS X, Windows XP still has some serious performance issues. There still appears to be the Windows "half-life" that was so widely mentioned in relation to Windows 95. case and point: my roomate bought a 2.4GHz Dell 3 months ago and runs Windows XP Home on it. I bought a 1 GHz Dell (the last PC I will ever by for myself pre-assembled) about 2 years ago, and I've been running 8.0 linux on it, since it came out (I think it was about 6 months ago?). While my roomates PC far outpaced mine when he started it up the first time, it has gotten slower and slower, especially after software installs, to the point that it now runs roughly the same speed as my linux box for normal operations like booting, opening and running various smaller applications (like web browsers, word processors, and file sharing programs). Also, the OS X machine, which has been running roughly the same amount of time as my linux box, has shown no noticeable decrease in performance, despite many software installs and uninstalls as well as adding and removing various hardware peripherals.
Through discussions with pro-Microsoft people, I've come to believe that the registry is the root of 90% of the evil in Windows itself (no comment on the rest of Microsoft). I've been told it allows a lot more standardization and intercomunnication within Windows. However, it appears that this causes significant performance decreases as the number of installs and uninstalls of software increase, making the system fairly unusable for someone like me, who likes to install, play with, and then uninstall several new shareware/open source apps a day (what can I say, I used to be an SQA engineer). Even for someone like my roomate who installed about a half dozen programs since he got his PC (3 or 4 games + printer software + camera software + MS Office) there is a noticeable performance loss.
-Venkman