I have made the leap from 32bit Vista to 64bit Windows 7....had to do a clean install, so did so on a new hard disk....and now have a dual boot (into Vista or Win 7). I have also done a clean install of FSX and am slowly rebuilding all my add-ins. Note that as mentioned in other posts, you cannot do an upgrade from 32bit to 64...it has to be a clean install. First on was the brilliant J41...absolutely no problems with the reactivation or running it in Win 7. I have to tell you all that i am getting significant improvements in both frame rates and loading time...which i guess is mainly down to the move onto 64bit. For those interested, I am running a system which is now 2 years old (CPU: X9650 Quad unclocked, 4GB RAM, Nvidia 8800GTX). All in all, I am delighted by the move across onto 64bit and consider Win 7 to be a big improvement on Vista. I hope this helps anyone who is contemplating the move! Chris Rosling