I'm looking into this myself at the moment.
Talk Talk do broadband for free pretty much, you need a phone line which is �10.50 a month from BT but then you transfer the phone line to talk talk and it's still �10.50 a month but you get broadband for free. but I've heard a lot of bad stuff about their customer service!
AOL are doing it for 4.99 a month on top of your normal line rental, but it's AOL and the software is horrible!! but you don't have to install it to use the service. However if you don't install the software they won't give you tech support at all, as thats not an issue for me AOL is the way i'm tempted to go (I really hate myself for saying that though!!!!)