Sky offer the family pack with 2 mixes for ?15, thats surplus to the 250 channels you get free ie. horror channel, etc.
That's for a hell of a lot more channels (at a guess anyway, knowing how badly cable sucks). I think they still give free box and installation. That's not to mention the offer your likely to get if you tell them about cable tv.
HDTV sky is launching next year btw.
http://hd.sky.com/default.aspx?id=4&pg=3