I am not familiar with a setting without a Modem. Ask your ISP if it is a regular DSL setting, and they put the modem elsewhere.
However, I assume that if it is connected to the NIC it is an Ethernet connection.
Get any of the Router that supports PPPOE.
Connect the Modem to the WAN input of the Router. Connect your computer to the available ports.
Make sure that your Network is working, before you start with the Internet config.
Read the Manual to find out how to configure the Router. Most Router is basically a Network component with IP. You start the I.E (Internet Browser). You type the IP of the Router to the Address entry, and you get the Router?s Menu.
Find the PPPOE setting, enter ID and PW (ignore the entry that ask for ISP info.)
Logout, and Reboot every thing. Start I.E go to Tool, Internet Options, Connections, and make sure that you are using the LAN (not the DialUp).
My take of which Router to buy:
Routers Compare.
For what ever it worth it seems that CW (Conventional Wisdom) claims:
1. Netgear RT314
2. Barricade 7004BR
3. Linksys BEFSR41
(3Com Entry Level Router is the samr as SMC Barricade).
These are all 4 port Routers, from a Router perspective the 8 ports counter part are similar.
I own few Barricades (Regular, and Wireless), and Netgear.
I like the Barricade (no real technological reason).
I would choose the one that has the features that fit the way you use the Internet.
Table Comparing thses Routers:
Comparing Cable/DSL Routers.
Link ? Courtesy of TallGeese.