My only concern about an Athlon 64 would be windows, and costs, could I just use the OEM WinXP that came w/ my Dell for an Athlon 64?
EDIT: OK let me explain a little more about my situation here, I could slap in a 2.4 - 2.53 GHz P4 into my current system for about $160 (A Dell) or spend $370 to get an Athlon XP, an Antec SLK3700AMB case, a new mobo w/ SATA, and pc3200 RAM. I'm just considering all this because prices are REALLY cheap now, and I feel that I could be doing more with my current video card.