Even moving up one generation would make a huge performance difference. Your time is worth something - don't be too cheap.
E.g. a 3 GHz Dell P4 (1 GB/4 GB Max, etc., etc.) small form factor box for $145 - http://www.usedcompu...tem.asp?ID=185254
Look around a little. Or tell us your budget and let us look around for you. :-)
Good luck.
Cheers,
Scott.