XP SP2 on my workstation, Fedora Core on servers, and a few Win2k3 servers at home. Work is all XP/Windows server (NT, 2k 2k3).
Did they fix that boot loop bug with SP3? I have not been bothered to try installing it. I actually pushed it out to some PCs at work while totally forgetting about that issue. Thankfully none of them crapped out. We're not really allowed to do updates though so it only went on IT machines and not anywhere else in the building. I told the L2 guy to go ahead and install it when he has to re image a machine, but that's about it. Getting the go ahead to install IE7 was a big feat on it's own.
We are thinking of possibly going with windows 7 in 2-3 years from now but it's just something that got quickly brought up, no true plans. Due to all the super crappy propitiatory apps we have, it will be a disaster given 7 is a totally different architecture then "NT based" operating systems like win2k/xp. I doubt most of those apps will even run. Most medical apps are huge POS. I'm sure anyone in healthcare will agree, even from users' side.