On the subject of cable, I get 10Mb from NTL for £34 / pcm. There's a 75Gb fair use limit on that, but I've exceeded that on many an occasion. But since I avoid peer to peer and don't clutter the uplink, which is the thing ISP's put FUP's in place for anyway, I don't have an issue. There's quicker ways than P2P anyway
As for adsl, adslguide's definitely the place for the latest deals etc.