I've been running with vista 64bit for over a year and windows7 64bit since early beta. All i can say is that i've never had any real problems to date and win7 seem s to me to run everything so much smoother. 64bit is the way to go. As for the above posters commets about vatism not working, well its well documented and very easy to fix. I use it all the time without problem.I would not hesitate to move to w7 64 bit (hence why i have 3 copies on pre order!)Dan