I have Comcast in PA, and I'm no fan of rising cable TV rates and their quasi-monopoly, but...
they'll have to pry my speedy cable modem from my cold, dead hands!
No way will I go back to 21.6Kbps dial-up Internet (the fastest I could get on our phone lines and no hope of DSL).
I know I could get satellite and keep the cable modem, but then they charge a premium for Internet access with no cable subscription, so it would just end up costing me more.
All I can say is keep checking on the DSL and if it ever becomes available, drop Comcast ASAP. Verizon DSL in MD can be had for $30-35/month. There is a website (I think it is www.dslreports.com) that is helpful to find out how far you are from the nearest station.