Comcast used to use Giganews, don't know if they do at the present time; with of course the mentioned bytes/month limit, either 1 or 2 or maybe more IF you pay extra for it.
Biggest problem of course with cableco's (and Comcast in particular) is they monitor all internet traffic on their systems, and will pull your account if they either see 'too much' traffic (whatever they deem it at any moment in time; read your subscriber aggreement...!); they have been known to pull folks accounts that exceed 100-200GBytes/month, or even much less for UPLOADS, which they have much less bandwidth allocated in their SHARED system than the DSL folks, which are directly connected to multi-gigabit routers at the CO's.
'Genererally' (but not always) cableco's have more speed in the download direction, but far less in the upload. Where I live I laugh at the Comcast commercials that continually mis-represent DSL, since my line (from Verizon, I also have two other DSL providers in my area as well) is as fast as 'turbo' Comcast speeds d/l'ing and triple Comcast uploading. At, I might add, less than half the cost. And, I run a continuous trasmit audio feed as well, which is prohibited by the Comcast subscriber agreements.
I must say it was only recently that Verizon 'caught up' with speed and pricing, but I had a line from Covad (national DSL provider) before they got their act together. So it pays to investigate the possibilities, not just go with who has more commercials (on tv or the tree's worth of junk mail I get in my mailbox every week).