Windows 9x not going past router

I had to rebuild a server for one of our offices. The only thing this server does is act as a DHCP server. Its address is 192.168.4.20. The router is 192.168.4.1. The Windows 2000 computers in the office can get out to the Internet just fine, but the Windows 95/98 machines cannot. In the Network Properties for TCP/IP, I added the default gateway (4.1). But these computers cannot access the Internet. They can ping 192.168.4.1, but not beyond that. And in WINIPCFG, the Default Gateway is blank, not even 0.0.0.0. Help!