DSL and NT

What is the cleanest (easy) way to share a DSL Internet connection with the rest of my network?
NT 4.0 SP6a server , 15 Win 98 workstations
All are static IP stations..in the 192.168.x.x range
Server has 2 NICs
DSL is not a static address, but assigned via DHCP from the ISP

I do have access to a Cisco 677 router, but have not set it up as yet
Any suggestions?