Windows 98 gateways

Our LAN has two gateways; one to a frame relay network and another that goes to the Internet. All the workstations are Windows 98. We have installed both gateways under the networking properties, however, when we try to go to the Internet the PC’sjust hang as if their attempting to go through the wrong gateway. How do I set up the workstations to specify that Internet (IE) requests are to go to one gateway and all other requests are to go to the Frame Relay gateway?