I want to install Windows 7 Ultimate 64-bit and I saw the youtube video: YouTube - How to Clean Install Windows 7 (Part 1 of 2) (and part 2). I got a question though. I already have Windows Vista installed, to install Win 7 do I need to manually un-install windows vista or wil this un-install on its own when I press clean install? if I have to manually remove it, how can i? Thanks.