It's actually pretty difficult to find 32 bit systems now. Everyone I've seen the past couple of years have all been 64bit

>Is it safe for me to assume that you were going from 32-bit XP to 64-bit Win7?
>- There was a 64-bit version of XP, though not particularly popular due to rarity of compatible 64-bit device drivers.
>- if the XP system was new enough to handle Win7, it's likely it can work in 64-bit -- so you might as well go 64-bit Win7 rather than 32-bit Win7 to avoid the 4GB memory address "ceiling". If system wasn't up to 64-bit spec, then it's likely already close to its "last legs" anyway so getting a new system was in order -- again, might as well go 64-bit to avoid the "ceiling" already looming ahead.