The simplest and most reliable standard wired router out there is a Linksys BEFSR41. I think out of the 50 or so I've set up, only 1 or 2 have failed. 50 bucks at Newegg, I know there are plenty of other units that cost less, but if you look around you may be able to catch a sale or a rebate deal on one. I have 2 of them here, both used, from customers that have upgraded to wireless. I figured I'd use one myself and keep the other as a spare and for troubleshooting in the field.
Installation is a snap. If you use connection software for the DSL (enter a username and password on the computer) uninstall it, make sure the TCP/IP on each computer is set to obtain IP address automatically, connect the modem to the WAN port on the router, connect the 2 computers to numbered ports, restart the modem, power up the router, reboot the computer, open a browser, surf to
http://192.168.1.1, leave the login name blank, use
admin for password, choose PPPoE connection, enter your username and password, choose "keepalive", apply/save changes, and you are online.
If your modem is handling the PPPoE and/or routing functions (no connection software on the PC's), before doing this you need to log into the modem's interface and switch the modem into the "bridge" mode. If you have SBC and were shipped a Speedstream 5100 modem within the past few months, this will be the case.