> b) want to upgrade their hardware at some point in the future from 32 to 64 bit, without having to buy the exact same software again Retail copies contain bo

> b) want to upgrade their hardware at some point in the future from 32 to 64 bit, without having to buy the exact same software again Retail copies contain both versions, OEM versions only contain the one and those aren't transferable to other systems anyway. Of course, if you upgrade some parts in your current build you might get shafted with the OEM version.