Ok, here's there deal guys.
I have both, cable and DSL. I have cable at home, and I have DSL in my apartment close to my University.
Without doubt, if we ignore the rest of the people that may be using cable at the very exact same time, head to head Cable will always beat DSL. Cable it simply, faster. Why?, because the medium for cable is a thick copper wire which is simply able to transmit more data. On the other hand, we have DSL. It transmits date through a higher frequency electric impulse than regular phone does, but still it does it through two tiny little twisted copper cables which in no way may compare to the one thick cable-tv cable.
Now, the drawbacks of Cable modem, as exploited by the DSL companies is what they call the "peak" hour. This is when it is most likely that most of your neighboards will be using the Cable modem at the very same time as you and would be playing Quake 3 all at the same time over the net and also at the same timedownloading mp3's, etc.. Well, eventhough highly unlikely, sometimes Cable modem is indeed somewhat slower. In contrast, DSL is "free" of that drawback. The DLS companies say that your DSL connection is like your phoneline, it connects directly to the server that provides you with internet access.
But, like I mentioned before, even with the cable modem rare fluctuations, on the average cable is still faster than DSL, plus it's better looking, :P
Now, to use either one of them in Linux, is a completely different story which I can go in to if you decide which one to choose.
have a nice day!