Filling up all RAM slots is a problem on all boards because only 2 full slots work at full speed, and then when you add another, it bumps the speed down.
Athlon64 rules, benchmarks say it all. Chess, yay - big CPU stresser, try playing a game with a video card without a T&L engine. That should show you how good the CPU is. Try loading 3dmark2000 v1.1 and place a TNT2 Ultra in your slot and then tell me the difference between scores.
Right now, I have regular applications going, running like a firewall 3dfx tray icon, SETI@home, and Norton Antivirus 2002. My CPU is being utilized 100%. But wait, I can still load up Day of Defeat and get great performance, how is that possible, maybe application priority or usage depends.