Ok, got the Sempron 3100+ running on a Chaintech SK8T800 Socket 754 Motherboard, 1 gig Ultra 512MB PC3200 DDR 400MHz CL2.5, no overclocking or bios tweaking, XP pro, running Samplitude Professional. My 32 track test file (16 mono tracks, 16 stereo tracks, eq and compression on every track and a handfull of plugins) never exceeds 20% CPU and 25% disk usage. This is damn good performance from a budget system that I'm embarrassed to say how little I paid to put together. Too early to make a call on the stability, but so far it's behaving itself perfectly. I would put this combo way up high on the bang for the buck scale, especially givin the ability to drop in an A64 3700 down the road when they drop from the current $500 avg price.
Standard disclaimer, YMMV,
RD