tboo, I'm a real proponent of 2.1 speaker systems, but if you're focusing on DVD and TV audio, I'd suggest you look at a 4.1 setup. And, for $150 you can't do better than the Boston Acoustics BA4800. You're correct in assuming that the sub in the BA4800's is beefier than in the BA790's. The 790's are great speakers for the price, but the 4800's are in another league.
The Klipsch ProMedia 2.1's are the current yardstick for 2.1's (unless you consider the Video Logic setup, but they're way out of this price range), but @ $200 they're more than it sounds like you want to spend.