Why not just get Windows 7 ,
Backup you're documents to a UBS or another drive then do a "clean" install
not an upgrade!
A clean install is the way to go, less headaches down the road.
You have 30 days before you need to get a product key to activate windows.
Just download the correct Windows 7 or 8 version you intend to buy because the key that comes with purchased copy only works for the version you install.
http://forums.maxperformanceinc.com/...download+links