Vista - Video Game Performance Issues in Vista

I am having some trouble with stuttering when I play certian games in Vista.
For example, when I play Halo 2 or Battlefield 2, it will stutter every 5
seconds or so for less than half a second. I think this is an issue with
Vista and my hard drive or something because whenever it stutters my hard
drive light flashes. Battlefield 2 does not have this issue under XP (I
can't say for Halo 2 as it is Vista only). However, Age of Empires 3 does
not have this problem in Vista or XP.

Can someone please tell me what is causing this problem? I think it may be
driver related or possible a bug in Vista (I have all of the latest drivers
and patches install for my system).

Here are my PC specs:

AMD X2 Dual Core 4800+
2GB or DDR2 Ram at 800Mhz
500GB 7200 RPM Seagate Hard Drive with 16MB Cache (SATA)
ASUS M2N-MX Motherboard with nVidia nForce 430 Chipset
nVidia 8600GT Superclocked Edition
Creative X-Fi Xtreme Music
Windows Vista Home Premium 32-Bit (I have not tried out the 64-Bit version
yet)

My PC scores a 5.1 in Vista's performance index.