Cable and DSL are very similar, except that DSL requires the use of a phone line and isn't available everywhere, whereas cable requires the use of coax cable (like CATV) and has a wider availability, especially in remote locations. Two drawbacks to cable are: 1) the bandwidth isn't guaranteed; it's "fixed" for a block of addresses, meaning that the more people use it, the lower the bandwidth per user, and 2) many cable companies don't allow service to only one person unless an entire block of addresses needs the service. At least that's how it is here in the U.S. (well, Texas). DSL, on the other hand, has a guaranteed bandwidth, but you have to be within 3 miles of the DSL "signal" to be able to receive it, and you have to have decent phone lines. (The old analog ones from way back won't cut it.) I have DSL at 768K downlink, and 384K uplink, and pay roughly about $40 a month for it. Friends of mine who have cable pay about the same amount and get about the same service, so I really don't think there's much difference.
One thing is for certain: once you go "broadband", you can't go back to 56K.

(Well, you *can* technically, but no one wants to!

)