I'm an instructor at a community college. I purchased a barebones machine from Tiger Direct thinking that I'd be able to install the Windows 7 OS offered by my college bookstore. Now that I have the disk, I see that it's intended only for upgrade, not for initial install in a machine with no OS. It is marked "Pre-existing OS License Required (Product Key Required)." I'd like to take advantage of the excellent deal I got on this OS, but I don't think it will work on a machine that doesn't already have an OS with product key. What's the easiest and cheapest way to get Windows 7 installed on this machine? Should I buy an older OS and have the Ultimate disk overwrite it, or should I just bite the bullet and buy a complete Windows 7 OS?