I've been running Windows 7 on two of my QA machines here. I own about 5 licenses for it, 3 via my Win7 Launch party, 2 purchased, and I have access to my company's technet editions. I'll probably still use Vista, though. I had a 500+ uptime before I started screwing with overclocking, and since then I've had about a 6-month uptime so, I'm stable, it does exactly what I want, and Win7 Doesn't have anything I don't already use. (I had fun with aeropeak and launchpads, but now I'm back to what I do on vista, anyway, so it's not realy worth it to me unless I build a new box, which I wont...for months).