I use 512 on textures... because with that i can preload to video mem, since my video card has 256MB. Does your video card have 256 or 128? With 256 preload textures in video mem would be notable faster than in system mem.
I run 1280x1024 (or whatever the 12xx res was) and it is ok playable, but not fast enogh to put all sliders to max, But my graphics board is much slower than yours.
I would try to run on 512 texture size, not as pretty as the 1024 but still nice.
Your CPU runs at a 12 X 167 Mhz, with a 167Mhz CPU FSB it is faster to run the memory at 167MHz too, so that is just fine.
Also i heard the sound card makes a difrence, i use SB Live which i suppose takes up cpu cycles.