Zen offer uncapped and always on service cheaper than wannapoo: ZenADSL Home 500 : Home and Professional - priced at only £21.27 monthly
I went with Zen because they are the best
on asdlguide.org and everyone I know, that uses them, has found them friendly and helpful.
My little modem/router has been up and running since the day my telephone line was enabled and feeds the SmoothWall Express box which I turn off when I'm away for more than a day or two.
I have downloaded several distros and update my Debian box and ubuntu/experimental box regularly with no problems (apart from my inbuilt stupidity)
I do not let my windows box connect to the outside world, paranoid? I don't think so