Windows 7 Professional Upgrade Version Standalone?

Hello,

I am eligible for educational discounts on Microsoft software. However, the only Windows 7 listed for a discount is Windows 7 Professional Upgrade Version (for $65). I do not have ANY operating system installed on my computer... can I still install this and be okay? Or do I have to have a Windows version already installed on my computer?

If this helps, I have a hard drive (that may actually be damaged, I need to check that) that already has Windows 7 Ultimate installed on it (educational version, 32 bit... I need 64 bit). I'm wary of using that hard drive and disk (I just moved the hard drive to a desktop with all-new components) because the disk had problems when I was installing... I had to take it to my University's IT for them to install it (the code wasn't working).

Thanks!