Games continuing to not work in Vista 64 or windows 7 64

Hi I posted a while ago about problems with my machine working with games such as Fallout 3, F.E.A.R 2, Age of Empires III, Perimeter 2, and Wolfenstein.
To start I bought my desktop machine very recently. Specs: Q8200 Quad Core, 8GB DDR3 Ram, 1 TB HD, ATI Radeon HD 4650 and I am booting a dual monitor system (2x 24 inch LG monitors).

I was having big problems in Vista 64bit playing these games because it would work perfectly for about 5 minutes and then there are beginnings of sound stutter and then video and sound stutter eventually rendering the game useless to play. After I quit the game, my entire desktop is slow and lagging (eg. selection tool on desktop lags as well as mouse movements). This lag dissappears after about 10 minutes (or doing a full restart).

I got fed up with this and for the next couple of weeks I proceded to dual boot my machine to XP and then Windows 7 came out so I am now triple booting with

- Windows Vista x64
- Windows 7 x64
- Windows XP Home 32bit

So on all three of these boots I have properly installed drivers.
My GPU temps are at about 83 degrees max and when idle are at 50 or below.
CPU temps are normal at 50 - 55 degrees max and when idle at 40 degrees.
The odd thing is that my games work fine and properly on my Windows XP boot with minimal problems but on Vista and Windows 7 I am still having problems. I am wondering if it is an emulation and compatibility problem. Please post your thoughts.

-SmallandLovable