most any isp that does not require a software package to connect should work. i.e. if you can setup a dun connection from windows w/nothing more than your username, password, and a phone number, you should be able to do the same from linux. if, however, the isp requires the software to connect you'll most likely have problems. so the question to pose to these isps that you query, is
do i need your software to connect, or can i setup a dun manually?
hope that helps.