In our business location, I use a Linksys router to distribute our DSL from MCI and to share files and printers. The problem is, the MCI DSL modem automatically sets a "Shared" Internet Connection Gateway on all computer on the network. So here is what happens, I can disconnect the DSL and will be able to file and print share and have no internet OR, have the internet and there is no file and print sharing... what if I use two NICs on one PC one for the internet, one for the network. Need help.

Sounds like you've got the modem and/or router configured in such a way that modem's configuration "wishes" are being passed through to your LAN.

You should be able to change that behaviour by reconfiguring the two devices; give us the exact make/model of both the modem and the router so that we have some specifics to work with.

Also- have you installed connection-related software from your ISP on the individual computers, or does the ICS/shared gateway configuration just seem to be automagically forced upon the systems by the modem?