Dang it, I was all excited to post that the ECS K7S5A had slots for DDR and SDR, and I got to the very latest post and my thunder was swiftly stolen right out from under me.
Yeah I was running an Athlon 2200+ with 384mb of PC133. Like you said, Ick. Huge performance jump to a P4 2.8 with 512 of PC400
Anyways, yeah you could build that system (with the ECS mobo) for under $300 yourself. Maybe a bit more with some peripherals, but not much more. When I built my comp with the ECS board, it cost me $250 for the mobo/chip/case/RAM when the ECS board was brand new. ha.