i have the MSI NX6600GT 128 GDDR3
i would recomend it to anyone who was thinking about getting one. It has HD and many of the eye candy factors of the 7 series nvidia cards. With the stock cooler it came with from MSI (ultra copper HS) it easily OC's 100mhz on the core and even more than that on the mem clock.
Runs on all High* Settings with AAx4 AFx4 and averasges 100FPS in HL2/CSS at 1024x768 res. just to give a comparison.
For the price i think its a great card, but def go with the 6800 if you can afford it.