I like the 64 bit better than the 32 bit. I have each in two PC's. I do a lot of testing and so I am sick of activating sometimes twice in a day. Lots of phone time being wasted. I use XP Pro as the master HD in all of my PC's. This allows me to uninterruptedly test lots of Linux OS as well as run Vista. Since I use XP Pro Corp version, I never have a problem with activation. That warning window that pops up at each restart is a joy compared to all of the crap that you have to go through every time you want to install a program or open a new program, and having to go through that permission crap.