Taken from cnet.com
Cable vs. DSL
Performance:
The winner: tie
So which service is faster, cable modem or DSL? No single answer will suffice for everyone. Cable's theoretical bandwidth limits are higher (but you'll never reach them), and because it's not dependent on distance from a central office, it's more consistent from user to user--unless your next-door neighbor is Blackbeard the MP3 pirate. With DSL, you'll generally get higher speeds the closer you live to the phone company's central office