Whats the difference?

I went from cable over to adsl about 9 months ago. I miss the 50k+ upload speed of cable compared to the 17k of my adsl. But then again I usually get 126k download speed on my adsl. Anyway, everyone around here is talking about dsl. Is that like adsl, in that it uses a program to dial up? or is like cable and always connected? My telephone company is offering sdsl in januraray. Will this be like adsl? or more to the dedicated access like cable?
The reason i ask is because im looking at a router and as far as i know, they dont work with adsl connections. Will they work with sdsl? Is dsl better than adsl and sdsl? Thanks