Hi, I'm using Vista Business. I'd like to pre-order a Windows 7. I've seen different kinds of Win7 products such as Pro, Pro upgrade, and Pro OEM on the website. My question is: If I buy Pro upgrade, does it means I just can only upgrade from my Vista Business (according to the upgrade path from MS)? If it does, for the next installation, will I need to install Vista first and then upgrade to 7 once again? One more question though Pro means using with any PC and Pro OEM means using with just one PC? Regards!