I have had both DSL and Cable. The cable was actually better at first, but as others have said, the more people, the slower. There were times that I would come home from work and would sit there waiting for pages to load. No matter what site I went to, it was slow. I was supposedly at 3megs down for $45 a month. I went with SBC DSL last year. They say up to 1.5 megs down, with a guaranteed 384k down (same as cable) for only $15 a month. The speed is always the same, and the only thing I notice slower with DSL over cable is downloading huge files. Cable would top out at somewhere around 600k, while the DSL only gets me about 180k max from any given site. Even then, the extra speed isn't worth the $30 a month that I am saving.
IMO, unless you want to share movies illegally, pick which one is cheaper.