no internet with xp upgrade

i have a compaq presario 1200 laptop that used to have
windows me but i have recently upgraded to windows xp.
since i have upgraded, i have not been able to connect to
the internet. I am currently connected to the internet
via a toshiba pcx2200 cable modem. I can either use a usb
or ethernet cable to attach my laptop to the modem. when
i try to open internet explorer i am greeted with "cannot
find server." any ideas about what is wrong and how to
fix it??? it is urgent please help!!!!!!!!