I have a PC with full legit W7 Ultimate installed. I also have a currently unused full legit Vista license. (originally came with PC .. I bought new OS not upgrade) I am building a new PC and wish to use the W7 license so I can put 64bit W7 on my new PC ... easy enough as it will be a clean install and I can use original install disk, it allows for 32 or 64bit install. The Q is the existing PC will then be 'unlicensed' ... when I bought it, it came with VISTA license ... For this old PC .. to pass it on to family ...can I - Opt A ... if I buy a Vista to W7 upgrade, can I apply this license without having to reinstall. ? (as this was a recent clean install) Opt B... if not can I re-install W7 and apply the upgrade license without having to install Vista first ? For obvious reasons I don't want to install Vista then upgrade to W7 ... prefer the clean install that exists? Hopefully this explanation is clear.