Internet Access

I have 10 client PCs running WINNT. They were moved from one location, to a location which recently switched from Token Ring to Ethernet. When I connected the Cat 5 cables, all of the clients were able to access the network, see all of their network drives. In IE5, I entered the applicable proxy server, port 80. None of the PC’s can access the internet. I successfully pinged each and every address, including the addresses for the websites, yet NONE of these PC’s will access the internet.Any suggestions?
Thank you.