Of course Jim meant GB, not MB.

Generally look for PC3200 modules (ECC, or non ECC - I believe it doesn't matter, as long as they come in pairs of identical modules). One thing you should know about - avoid the "high density" modules you can find on various eBay's - they surely won't work. No "High Density", no "AMD chipset compatible". Look for "Low Density" or "Intel chipset compatible" and you'll be fine.