If I were you, I'd upgrade the video card and RAM. If this puts to much burden on your budget, then down grade the CPU/Mobo.
Go with the AMD 2500+ and an Asus board. This combo will be about the same amout as the 64bit 3000+ alone.
Upgrade to at least 512 RAM. The PC3200 is good. Check the recommended brand of RAM to use in the mobo.
Also upgrade to at least a 9600xt. If you can swing a 9700Pro - 9800xt, that'd be even better.
Finally, get yourself a good heat sink/fan to keep the CPU cool.
Check out www.newegg.com
for all your computer needs. It's a great site and very easy to navigate.