DSL can be a good solution if you are very close to the supplier, or main switch. The problem with DSL is that the signal degrades rapidly over distance. If you are 7 miles from the main switch, your speeds may not be any better than dial-up! DSL is also heavily affected by how many people are on the line.
I used to live 800 feet from the phone company, and my DSL speed was actually quite good, very close to what they advertised most of the time. I moved only a few blocks further away and ended up going to cable because the DSL speed dropped so badly. Anyway, the modem really has little to do with it, its all about your ISP, distance to them, and how many people are on the same line. Condition of the line its self also has a big impact.