Elusive Internet Connection Sharing

i've got two freshly formatted computers(Win98se),connected via 10/100 ethernet and Linksys etherfast/dsl router...
the "main" system is connected to the internet with a 56k modem...
both systems can "see" each other,and can share files just fine...
but the second computer cannot access the 56k modem,all i get is "the page cannot be displayed"...

i'm aware the "main" computer must have "internet connection sharing" enabled in "add/remove programs",however when i do enable that feature,the computers can't see each other at all,and i get a pop-up that say's "Internet connection sharing is disabled make sure internet connection sharing is enabled on only one computer"...it is only installed on the main system...

to get the computers to see each other again,i have to uninstall "internet connection sharing" in "add/remove programs"...
and needless to say,no internet on the second computer...also i have reset the linksys router as well...

looking in the network window on the "main" system;
"Client for Microsoft Networks"
"Dial-up Adapter"
"Linksys LNE100TX(v5)Fast Ethernet Adapter"
"TCP/IP->Dial-Up Adapter"
"TCP/IP->Linksys LNE100TX(v5)Fast Ethernet Adapter"
"File and Printer Sharing for Microsoft Networks"
Primary Network Logon is "Client for Microsoft Networks"

the "second" system looks like this;
"Client for Micorsoft Networks"
"Dial-up Adapter"
"Xircom CardBus Ethernet 10/100"
"TCP/IP->Dial-up Adapter"
"TCP/IP->Xircom CardBus Ethernet 10/100"
"File and Printer Sharing for Microsoft Networks"
Primary Network Logon is "Client for Microsoft Networks"

i'm hoping you guru's will be able to point me in the right direction,as i'm sure this is a very simple problem...

More than likely the Linksys DSL router has all of its features turned on and is trying to be the Internet connection device for your two computers. That is what your main computer's ICS installation is complaining about.

Although I'm confused. Do you have DSL?

If you do why are you trying to set up ICS on your "main" computer with the 56k connection? The Linksys should do all of that for both of your computers.

If you don't have DSL, you have to turn off all of the features of your Linksys DSL router and make it act like a dumb switch in order for you to enable ICS on your main computer.