I'm not at all pleased with my frame rate after asking a few others about theirs. I'm seeing between 8 and 15 fps on my system in SL. Meanwhile my wife has my old computer (albeit with a smaller monitor) and she gets 25fps with an old 128mb 9800 card and a P4 3.0.
My system is as follows:
Abit AW8D mobo
Pentium D 3.2
2 GB (2 x 1GB) OCZ DDR2-800
Raid 0 SATA
ATI 2900XT 512 MB PCI-E
24" LCD (1920 X 1200)
XP Pro
I went so far as to throw together some inventory parts to do some testing, as well as swapped in a cheap x1650 video card. My results are astonishing! On a Pentium Dual Core 1.6, 512 X 1 with the 1650 video card and XP Pro with similar quality settings, I see rougly the same frame rate! Maybe 1-2 fps lower with a busy location.
I've also done a clean install on my old system, changed power supplies, put the 1650 in (almost identical performance), tried every combination of driver and tweak I could find, overclocked the GPU, overclocked the CPU etc. All I've managed to do is further lower my FPS.
I cannot break 15 fps on a busy SIM and 20 on a sparse sim. Meanwhile my friend online has a 8800 and sees over 40fps in the same location I barely manage 12 in.
I've also lowered all settings to minimums, decreased resolution, etc etc with minimal increase in FPS.
So, after doing a lot of research, it seems the 2900XT is just not a very good card despite it's $400 price tag when I bought it. Does anyone reading this have a similar setup and are you seeing my kind of frame rate? I've eliminated everything but the card at this point. I should have kept my 7900GT.