I have had no problems with service pack 2 on the three of my home PC's and work PC's. I also have it installed on about 125 PC's on our network with no trouble at all as well. We are using them as test mules before we deploy the rest of the building and so far it has been very stable no problems at all. Of course we had to disable the firewall since we have our own
first view i got of sp2 was that its anoying. might be good for corporate use but for home use you're better off not having it i think. the process count increases with 8 processes, if you try to release all your memory and cpu before you go into a game (like me i dont start a game without having less than 20 processes running) then you're better off not having it.
SP2 messed up my computer totaly the first time I used it. But I think it has been updated slightly due to the overwhelming mass of e-mail Microsoft got after its release. I recently installed it on a freshly installed version of Windows XP and its fine.