I have the msi 8800gt oc, Just got it two days ago and couldn't be happier even with a 2.0ghz e2180 cpu! It stays very cool with the zalman cooler that it comes with. 40*C idle and hyaven't seen it get any higher then 52*C load so far running Battlefield 2, Company Of Heroes, and Counter Strike Source all at max settings plus AA/AF maxed @1600x1200
I would get the MSI 8800gt oc if I were you...I was in the same position and think I made the right choice
BTW, with the latest nvidia drivers, the msi 8800gt only uses 30% fan speed for 40*C...dunno how much under load, but Ihaven't noticed it get ANY louder