I built my rig in 2010 with Windows 7 32 bit thinking I could run most of my games off of it for a long time until I hit a problem earlier this year when I bought C.O.D Ghosts for PC. I currently have Windows 7 32 bit but from what I hear it is not able to even start up COD Ghosts with 32 bit at all. So my question is which version of Windows 7 Home Premium do I need to upgrade from 32 bit to 64 bit. Do I need the Upgrade version or the system builder version?