Ran into some problems with GRID when I first installed it on my secondary machine and thought I’d share the fix. System specs are below:

AMD Athlon 64 X2 3800+ @ 2.35GHz
eVGA mATX nForce4 SLI
2×1GB Corsair Value Select
2x eVGA 8800GTS 640MB SSC
OCZ GameXStream 600W
Seagate 320GB 7200.10 SATA
Samsung DVD Writer
Silverstone SG01B-W

All of this usually has no problems powering a 1680×1050 21″ display, but GRID would periodically (usually within about 10 seconds of starting a race) start to stutter in a way that looked a lot like hard drive buffering, but lasted for too long (5-30 seconds) and then it would go away for another 10 second. Very annoying.

The problem, it turns out, is mostly isolated to SLI systems running Vista without Service Pack 1. Driver updates and other standard fixes didn’t do anything, but an update to Service Pack 1 took care of it right away.