I got your mail, but I still don't understand the problem. lol
Try downloading the latest drivers for your motherboard, latest graphics drivers, even sound drivers. Directx 9.0b is out, you can get that on micro$oft's website.
14000 marks in 3dmark2001 sounds about right. Although I would of thought that reachable with a Ti4600. I don't know.
I'm beginning to think it might be the RAM that is holding you back. Don't get me wrong, you have plenty of it. But if there is a bottleneck it will be the DDR266. If the processor is 800 mhz fsb then you really need DDR400 (PC3200) but if it's 533mhz fsb then it just might be that that is the most you can get out of your system. The graphics card is the best part, and if the CPU, mobo and RAM are all 133 mhz clock speed (DDR 266, 533mhz fsb) then they are the bottleneck. It's still a great system though, and most games should run well with high/max details. Just don't use GP4 as a benchmark for that last statement.
Baz