I have found a tweak to the ntfs file ssytem that happened to fix my stuttering issue.. wqas so bad I could barely play (core 2 duo e7200 OC'd 4.03 8GB of ram 8800 GT 512MB)

This fixed it for me Type in the following command to increase the cache setting:

fsutil behavior set memoryusage 2

To check the current value, type in this command:

fsutil behavior query memoryusage

To change the setting back to the default, use this command:

fsutil behavior set memoryusage 1