If you're going to install Vista, yes you need a license, it doesn't matter if you're not going to run it.From XP to VistaFrom Vista to Windows 7
said by Microsoft :
Cross-architecture in-place upgrades (for example, x86 to x64) are not supported.
So, if you want to go 64 bit you're going to have to reload.--
Progress isn't made by early risers. It's made by lazy men trying to find easier ways to do something. ¯ Robert A. Heinlein