I am currently running the 32-bit version of XP Pro and I want to "upgrade"
to the 64-bit Vista Home Premium (I have a the Intel EE6600 dual core, so I
can handle 64-bit). I understand that I have to do a clean install, but I'm
confused if I can buy the Vista Home Premium Upgrade (since I do have a
active copy of XP Pro) or do I have to pay double for the Standard (Full)
version.

Also, is there a seperate box for 32-bit versus 64-bit Vista Home Premium (I
see different ones available for OEM, but not for the retail box).

Thanks in advance for your help