While dually Athlon's served me well for years, I bit the proverbial bullet and did it. I sold off my Dually AthlonMP system, and picked up a fresh, black-spanking-new Shuttle XPC SN41G2B-V2.0, with an AthlonXP 2500+ CPU and a GB of DDR RAM.
I couldn't be happier. This thing is quiet, smooth, and performs great. I can add in high-end graphics at any time, but the integrated gf4-mx does everything I need it to... for now... until I get a copy of D3, of course.
For my purposes it runs great, and it has the upgradeability I want should the need arise, and it runs cooler than any P4 SFF system I've ever heard of. And of course Soundstorm kicks everything else out of the market.
Cheers! <raising a pint of Guinness...>