I'm planning on buying Windows Vista and a new video card. I noticed the OEM version are much cheaper. If I buy one of those and backup all of my files, can I install it over a Windows XP Home installation? I don't care if it formats the drive. Is there something I should know about a OEM edition? And is this video card compatable with Aero? Also, is a 1.50 GHZ processor okay? Thanks!