Used the provided CPU and GPU benchmarks. Only included one run because runs 2, 3, and 4 were identical. IIRC, 1024x768, all details on low except texture, shader, and object on medium. Opteron 165 @ 2.7ghz, 2GB, 7800GT @ 445/1070, XP.
162.18:
CPU
!TimeDemo Run 2 Finished.
Play Time: 37.76s, Average FPS: 39.73
Min FPS: 9.90 at frame 200, Max FPS: 51.26 at frame 354
Average Tri/Sec: 17765840, Tri/Frame: 447219
Recorded/Played Tris ratio: 1.61
GPU
!TimeDemo Run 2 Finished.
Play Time: 52.96s, Average FPS: 37.76
Min FPS: 19.99 at frame 289, Max FPS: 68.36 at frame 1022
Average Tri/Sec: 22307648, Tri/Frame: 590713
Recorded/Played Tris ratio: 1.55
169.01 beta
CPU
!TimeDemo Run 2 Finished.
Play Time: 37.75s, Average FPS: 39.73
Min FPS: 7.97 at frame 200, Max FPS: 50.91 at frame 348
Average Tri/Sec: 17772178, Tri/Frame: 447268
Recorded/Played Tris ratio: 1.61
GPU
!TimeDemo Run 2 Finished.
Play Time: 53.00s, Average FPS: 37.73
Min FPS: 19.95 at frame 289, Max FPS: 68.93 at frame 1019
Average Tri/Sec: 22285528, Tri/Frame: 590583
Recorded/Played Tris ratio: 1.55
Almost no change. Actually more of a drop, but not significant. Though with the CPU demo, using the new beta drivers dropped the minimum FPS by 2! I'm not gonna bother to switch back though. Would've liked to see some improvement with this "special Crysis" driver. Although when I played through with the old drivers, I got a nasty 5-10 second pause several times. It almost felt like it froze up but it always came back after a while. It didn't seem to coincide with heavy action or low FPS... just paused completely several times every 10-15 minutes. So hopefully the new driver fixed that, but I haven't tried it yet (didn't ever pause like that with the benchmarks).
Also, 2GB of RAM seems to be perfectly fine for me. Any slowdowns I had were definitely from the CPU or GPU... I noticed no swapping or obvious signs of low memory.