I have Comcast and almost always get over 20 MBPS. That's about 3 times faster than what you say you're getting with DSL. I can download a 2+ GB ISO file in about 20 minutes.
I've been a CenturyLink DSL customer for many years; back when it was Qwest and before. It's been fine, and I get close to the 7 MBPS advertised. But I see ads on TV by Comcast saying that DSL is slow. I've talked with some co-workers who have Comcast (now xfinity) and they're getting something like 20+ MBPS. Man, that sounds fantastic! Unfortunately for me, Comcast/xfinity isn't available in my area.
But the bottom line is this, is cable really faster than DSL, or is it just advertising?