A little while ago I read an article about the Geforce 4 performance's and it's performance was barely as good as a Geforce 3 (Or am I mistaken here ??? )
comparing those 2 cards is like comparing the geforce2 ultra to the geforce3 ti200.
one card is clocked higher while the other has better features.
id go with the better features so go with the geforce4 ti4200 (wich is in fact alot faster than the geforce3 ti500)