First of all I wouldnt recomment deleting windows entirely. Heres why:
(1) I have SBC and when I moved house to avtivate my account at my new address I had to go to a webpage that is viewable in Internet Explorer ONLY - no linux browsers I tried could view it (konqueror, mozilla, netscape 7.2, netscape 4.7).
(2) If you cant connect in linux you can boot into windows and use that to look at forums like this to diagnose the problem.
(3) You only get a username and password after you set up the connection in windows. You cant get it using my method in linux - my method asumes you know your username and password.
I did it by going to:
Download the program. Then
(1)su (you have to be root to install it)
(2)rpm -Uvh rp-pppoe*.rpm
setup is straightforward. You might get away with not doing anything with dns option - otherwise try server option.
This isnt a unique way to connect , just how I did it. Someone else will have to help you with other methods.