Max

I have a vista desktop which i rarely use, and a MacBook Pro which i use allll the time for video editing.

Since Mac's arent all that great for gaming i decided im going to super upgrade the windows machine (Intel Core i7, 1tb HD, reallyyyy nice Nvidia graphics card etc.) so i'll be able to play all the games for years to come on maxed settings. But, from what i've seen of the PC, Vista is a terrible OS (constant virus warnings, unresponsive/cluttered interface), and i wanted to know how much it is to upgrade from Vista Home Premium (32 bit) to Windows 7 (whichever version is best for gaming cuz thats gonna be it's sole purpose). I have a Windows XP disk if that matters, but i'd like to have the latest OS if possible.

Thanks!!