Problem connecting to inetrnet using a d-link glb 802c modem

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http://www.linuxforums.org – I am using Ubuntu 10.04 LTS. my PC is a Compaq Presario SG3043IL with a D-Link GLB-802C ADSL 2+ Router. previously i was not even getting connected to the modem but now some how i have connected my ubuntu to the modem but no way can i connect to the internet. the internet connection workins fine whenever i log on to my XP. need help to connect to the internet. (HowTos)