The best 2.1 system I've heard about is the Altec Lansing MX5021 THX 2.1 Speaker System.
The sound is supposedly the most realistic of any 2.1 system at that price, with seperate mid ranges/tweeters and sub.
If I didn't want a 5.1 system, I would have got them.
The Altec Lansing 5.1's though are no where near as good, and neither are the ones above this, with the thin panels.