They have both version of Vista coming out. There are both versions available for download off of connect. AFAIK the final release will have both version on the DVD and you get to choose which version you want to install. But this is not confirmed yet by M$. I have used the 32bit (since that is the only type of system i have) but i know people that have used the 64bit. There is also the Server version that will be available sometime in 2007.