Using windows server 2003 right now. WOrks great and is stable. Cannot get direct x to work out, asio devices are weird. I can use them but but at the same time as wmd drivers and so forth with samplitude. Fruity loops will not work either, which i make lots of drum click tracks with. My buds studio is still on XP PRO SP1. Works mostly. have had a ton of problems in the past with it though. What are you guys using and what issues have you had?