Good resolution for oblivion and the witcher?

Hey guys,

I am using a desktop with:

Factory speed E6600 D2C
MSI 8800 GTS (G92) 512MB
2GB RAM
7200 RPM Hard Drive
on EVGA n680i motherboard.

I have been playing Oblivion and The Witcher games on this computer for awhile on 1600X1200 setting, but I have been getting lags and stutters here and there (sometimes badly). I am wondering if there is anyone who has a system similar to mine and played games I played there. Some suggestion on what resolution to use, AA, anisotropic recommended would be helpful. I mean, I don't care to make it look perfect at the cost of performance sacrifice, but eye candy is always better than none Thanks in advance.

for oblivon, i would just play about with the settings till it is fine for the witcher, i have not worked out that one apart from the draw distance, only real way of ensuring smooth play but then again, your system is better than my own so i am surprised you suffer stutter, i think it is just both game engines ain't the smoothest, pretty inefficient on both counts i would say.