As has already been suggested, the Epox 8K5A2 or 8K5A2+ with RAID and LAN are excellent choices. The 8K5A2 can be had for ~$85 @ Mwave, and the 8K5A2+ can be had for ~$99 @ Mwave. If you haven't got an XP yet, I would go with one of the $54 1600+ @ Newegg, and pick up some good PC2700 DDR. Here's a nice little config..
Epox 8K5A2 or 8K5A2+
1600+ from Newegg
Samsung PC2700 from Kommax for $126 (512mb)
With those three items, you should be able run the XP @ 166mhz (333mhz ) FSB, for a speed of 1.75ghz (2100+).
Feel free to pm me with any questions you might have...