Internet Disconnected Server Not Found

I having problems to conect to the internet after i install my graphics card.. is a asus radeon hd 5670 512mb all the services are on and the dsl cable is conected properly after that a buy a usb network adapter of 300mbps.i install it detects the modems i enter the securyty key properly 3 minutes later of scanning says that failed to conect t wire456 [name of the modem] the computer uses windows xp service pack 3 when i try it on my windows7 ultimate pc it works all ok i remember that later when i install the video card i uninstall some programs maybe i uninstalll some of the drivers but i dont now wich drivers.