Cable and DSL are in general about the same performance wise. Really it is highly dependent on the site you are connecting to.
DSL has the distance restriction, you must be withing 18K feet of a telco switching station. Cable has the user/bandwidth issue, the more users the less bandwidth per user.
I don't know what everyone is bithcing about price wise. I pay $40 a month for 786/128 ADSL from Ameritech, I live in the cleveland, OH area. On average I see download speeds of about 70-90Kb/s. Playing Quake III and Counter Strike on line I typically see ping times in the 50-100ms range. I have had the service for about 8 months and have no complaints, it has only gone down once when a firmware upgrade went south on them. Lost about 5 days service but was not charged for it.