Which bit of upgrade your PC don't you understand. 6600s are wasted in museum pieces as the processor cannot feed them fast enough...:sp3poskin

well, pcupgrade would be a waste since I'll get a brand new computer by christmas anyway.

I'm just asking because there isn't much difference when I turn down
resolution etc, and trying similar graphics in GTR runs much better...

But I think it's common for many racinggames that the starts are
troublesome, after a few laps the field are spread out, then it's much better

Dont know if your P4 has hyperthreading, but try to disable/enable HT (depending on setting u use now)

Some programs dont like HT that much.

hope u find a fix for your problem

You could try downloading the "minimum" settings from the LFS benchmark site and see what kind of frame rate you get. Those settings are as bare-bones as you can get, so you should get the best frame rates possible. If you have a second computer (even a somewhat slow one) you could start a dedicated server on that machine and add a few AI cars on it, then connect using your current machine and add a few AI cars and yourself. That way you're splitting the processor load for the AI cars (and the packet delivery) between two machines. Your FPS should go up significantly.