Just so you know, as an FYI, you can order 64 bit media from MS for a very small fee (like $10) as your same product key you use for 32 bit is valid as a 64bit product key, and can be activated. Just an FYI.
Right now, though, most things have performance issues in 64bit Vista, and Vista is always a step slower then 32bit (due to drivers and WOW management for 32bit apps)