I have and have installed two DSL systems with two telephone ISPs, Verizon
and Windstream (formerly Alltel).

My experience has been the ISPs do not support Linux as the Install/Setup
software. Once I have the initial setup connection achieved with Win 2000 I
fired up or installed Ubuntu. Like magic, Ubuntu didn't have to be told
anything about the Ethernet - DSL connection. Like true user friendly
software, like E.T. the Extra-Terrestrial, it "called home", going to
www.ubuntu.com as its homepage. After a few seconds a message came up saying
my current installed software needed updates. Its amazing that although
Windoze and the DSL modem were made to work together. They can't do this
automaticly and Linux can.

The DSL modems Verizon and Windstream provided has a USB and 4 Ethernet
ports plus a wireless Ethernet. Never used the wireless or USB ports but
have had more than 2 Ethernet PCs connected with no problems.

Like mentioned earlier. I would be good to contact your provider, get the
model of the DSL modem and see if they NOW support Linux. If not come back
here with the ISP provider and modem and see if anyone has had any
experience with them.