Which Vista 64 bit Version?

I plan to get a 64 bit version of Vista for a new computer build.

Is there any difference between Vista Home Premium 64 bit and Vista Ultimate 64 bit? Other than - PC backup and restore, Fax and Scan, Remote Desktop, Drive Encryption?

I don't think I need these extras from Vista Ultimate for home use, but I did not want to sacrifice performance, speed, etc. if there was a difference.


Also, for the 64 bit version of Vista Home Premium, would it work to purchase the 32 bit retail version SP1 off E-bay and then request the 64 bit version from Microsoft (for and extra $10)? Looking for the easiest/cheapest way to get Vista Home Premium 64 bit without getting the OEM version?

i'm planning on getting a new build and confused about the vista OS. i've read other threads and decided on 64bit. and i also read that the home basic version of vista detects a dual core processor as a single cpu (didn't really understand it)
what are the differences between the vista versions? which are good for gaming?
prices here for vista are expensive, ultimate versions are AED1200+ (~$326) but if they give better performance etc i'd go for it
thanks in advanced