OK, I see zenmaster's point. I use A64 based processors myself. A single core Sempron probably would be faster (and you get the motherboard).
But, I understand your interest in the dual Intel system. I once built a dual Socket370 PIII system. Sometimes its just fun to complete a project (and the Slot2 processors you're looking at are cheap).
Let me see what I can find on the 450 PII's VRM.