Before we take more time to think about what goes wrong, do you happen to have win XP SP2 installed by any chance? SP2 limits the outgoing connections and is a bitch. You might want to look at this thread if you want. (if you a new to computers, it might be easier to uninstall SP2 in add/remove programs)
http://gnutellaforums.com/showthread...ax+windows+sp2
If no SP2, and no worky: configure the modem as bridged mode (making the modem only act as a modem, no router) look there to do so:
http://kbserver.netgear.com/kb_web_files/n101306.asp
*WARNING* You'll have to configure the PPoE connnection on your computer now to connect so have in hand the connection settings first!!!! To configure PPoE in XP, go
http://www.wown.com/j_helmig/wxpadcon.htm
Bonne chance!