I asked my DH, since he still uses his 500 mhz PIII. Most can take up of 1 GB, of memory. Cleaning out excess programs will help a lot, if you are able to even reformat your HD and start fresh, that can really help. That said, it should be find for email and surfing, you may have a few program/site problems, but overall not bad. A better investment would be a broadband connection then a faster computer. That said, he just upgraded to a 24" iMac and really loves it, but the old machine is still in use, fully networked, and working great.

P.S. XP should run great, better then ME or 98...