Not able to get to Internet

Ok, here is the deal the only common factor is Windows 2000. We have had several network cards not being the same model or brand different computers and not been able to browse the internet. We have also had brand new machines out of the box that were unable to browse the internet. But, have all network functions are fine Email, Network Neighborhood, etc. But, not able to browse the internet. All the service packs and updates are done on the computers and re-applied. The only fix that we have found is replace the network card, but is there a FIX for it besides replacing the network card. Need your assistance in this matter. HELP 🙂 For quicker responce email me the answer you post to wroming@ci.killeen.tx.us Thanks a bunch.