you're using a rather old CPU which has an FSB running considerably slower than your RAM...so not only is your CPU slow, but it's also bottlenecking your RAM.
The most powerful thing in your system is the 6600GT...the rest of your system is far behind the times and your money woulda probably been better spent on upgrading the CPU and probably mobo before getting that card.
Sooo, just be thankful for that score you got really