Make sure you ram matches the fsb of the cpu.. Try overclocking fsb by 10-20mhz.. Make sure you motherboard has support for agp 8x, and is running in agp 8x.. Benchmark your system with sandra, compare it to other results.
Nothing thats cheap, the 6800 Ultra is not cheap. If you want something better, its going to cost more. The only way to go would be the X850 XT, witch is PCI Express and 700$. Just get the 6800 Ultra. Even on normal settings that game looks great.
