1. Regarding the motherboard, you'll find that an nForce2 board will give you a lot more performance and bang-for-buck (its more expensive but not horribly so).
2. Regarding the CPU, i think you'll probably want to get a "normal" AthlonXP or at least a mobile one running off the 333Mhz FSB.
3. Good call on the video card although I think the GFX5500 can be had for quite cheap and has more performance
4. As for gaming, you'll definitely want at least 512MB
