I've just established that my copy of Windows 7 home premium only uses one of my two duel core processors on my 1,1 mac pro. I need to upgrade to Windows 7 professional for it to use the other processor. I only use windows for games and would like to know if my system is/will become CPU bound unless I upgrade to Windows 7 professional. I've run a test running Portal and coming out and looking at the processor history in Resource Monitor and both my cores on the single processor it sees have been maxed out while running the game. I'm currently using one of the new Apple 5770 graphics cards but am thinking about buying another one to run under cross fire. However, if I do this it looks like I will need more CPU power to make use of it so I will have to upgrade to Windows 7 Professional. My concern is will the games use the 2 processors if I upgrade. I would hate to spend £130 on Windows 7 professional upgrade only to find that games don't use the extra processor anyway.