Why won't wireless internet work on laptop?

I used to have AT&T wireless broadband (formerly SBC) on my laptop. I am no longer with them and recently I wanted to install a wireless. I got the card, the router and I was able to connect to the internet on my personal computer but whenever I tried to connect through my laptop it would dial up and never connect. It says that I am able to communicate with the router but it never connects to the internet. I have looked everywhere I can think of to make sure all of the AT&T components are deleted or removed. Still it will not connect. What is the problem? Thank you.