Cable modem on W2K network w/AD & DHCP

I’m trying to install a cable modem and 4-port router on my Win2K network at home. The server is running W2K Server w/AD and DHCP with internal addresses in a range of 192.168.1.16 – .1.48. I can ping the router from the internal network, but I can’t ping the Internet side unless I connect to the Internet (using another means). In other words, I can’t seem to “cross” the router to allow my network to share and use the cable modem. Any ideas?