Well, I'm no Mxy, but.....
- first, are you sure that the laptop actually used the cable, and not a wireless connection, to connect to the internet?
- or do you have another computer, which definitely doesn't have a wireless card, with another cable you can try. Looks like you tried another cable, was that from a working computer?
- when you connect the cable, does a light go on where the cable plugs in?
- assuming XP or Vista, open up the network connection - does it say connected? Either you can click "Disable", then "Enable" and see if it clears up, or you can click on the Support tab and click "Repair" and see if that helps.