XP SP2 thoughts
I got XP Service Pack 2 today. So far so good, I've only noticed one compatibility issue so far. The pop-up blocker in IE is nice, though the default option with that warning bar is annoying. Not sure what they were thinking there.
The security center is interesting. Hopefully once it lands on people's machines it will make a difference in the worm/virus impact, but I'm still convinced that human nature will continue to circumvent any measures Microsoft puts in place.
The one incompatibility issue is with Avid Xpress Pro, but I don't have their latest version (downloading now). The serious upgrade still isn't available for download unfortunately. Of course, a security fix last year caused the UI to get hosed, and Avid wrote it off as Microsoft's problem. In the old days, Avid could require very specific hardware and software configurations, and could get away with it because customers would need to spend at least $10k in the first place. A dedicated, specific machine came with the territory. Ever since they started targeting the film geeks and cable access crowd, they don't seem to understand that those requirements are ridiculous for people that use their machines for everything.
Edit: The 4.3.5 version of Avid still doesn't work. Bummer.