Hello I am using window 7 RC version and as you know the RC is coming to end so i was wondering i can do a clean installation with the window Vista that I used before then use window upgrade home pre version because I'm running window at 32bits but later i want to upgrade my computer and use 64bits which means i cant use OEM cause it only give 1 version and dont want to pay for a full version
Keys are interchangeable between like verisions. If you know someone with a 32bit oem disc you could use it with the key you get from a oem 64 bit verision. It works the other way around too.
What you plan on doing will work too but I would hold off all together on getting windows 7 untill your ready to go x64. There are not a lot of big differences between vista and win7 that would have me going through the trouble your describing.