I'm running W7 64bit on my Toshiba Satellite X200 having upgraded it from 32 bit Vista. It runs perfectly and noticeably faster with no software compatability issues and takes advantage of the full 4Gb of RAM which Vista didn't. Unless you've got some very old hardware you shouldn't have a problem as 64 bit drivers are available for most things these days. Do a clean install and your old Windows installation will be saved to a folder so that you can 'rescue' the stuff you forgot to back up!