The latest NVIDIA driver (169.21) is the driver you should be using. All of their drivers have universal architecture, so you can't go wrong with the Forceware line. Just make sure you install the 32 bit XP drivers and not the Vista.
As fr as Stalker is concerned, it's just part of the programing. I run an AMD X2 6000+ AM2 with an ASUS M2N32 SLI Deluxe, 2 gigs of RAM and an 8800 GTX and it still has stutter, so that's normal.