thats a TNT chip I believe...or TNT2...can't remember...doesn't really matter....are you using the Nvidia reference drivers?.....if not go and download latest drivers...think the site isn't up, I can't log in but anyway...
Nvidia.....That should do the trick....Nvidia drivers work with all Nvidia based Video cards...from TNT - GeForce3....they all use the same drivers....you can never rely on Diamond for drivers.
heres a link for driver...
link....site seems real slow for some reason...good luck to you.