Gamersdepot.com has a good review of the new 2.1 system
here.
They mention comparisons between the 2.1 and the 4.1...a few tidbits...
"Another important thing to point out is that the 2.1s have no power compression or limiter on the subwoofer, which means you can crank it to your heart?s content and it?ll keep pushing the sub louder and louder. As you may recall the 4.1 system has a limiter/compressor on it that turns the subwoofer down after a certain amount of volume. On the backside of the subwoofer enclosure is the connection plate that ties the whole system together. Along with the power switch, there are the speaker terminals, the pre-amp input from the satellite control module, and a 12 Amp fuse..."
"The satellites in the 2.1?s have also been updated. Using the same great drivers as the 4.1?s, these newer satellites have a revamped crossover network in them that results in a midrange section that seems more ?alive? and full. Included on the right-hand side of the satellite control module, you?ll see that Klipsch has made another improvement as well. After listening to suggestions from the press and their end-users, Klipsch has made it ultra-easy to instantly hook up headphones or your personal audio device straight into the speaker. This saves you from having to dig behind your PC and find the soundcard jacks..."
"There?s also a hidden talent that the 2.1s have that helped them to replace our current v.2-400s as our reference system. Have you ever been watching a movie or playing a game only to have the rear audio channels sound thin? For example, in the movie The Matrix during the helicopter scene, did you know that as the blade on the helicopter spins around, that you can hear it go around the room? The surround sound information on the DVD is actually trying to send a very low frequency signal from front to back. We?ve found our answer to this dilemma, and that is to get two sets of the 2.1s and hook them up as a 4.2 loudspeaker system. Doing this gives you two satellites in the front, two in the rear, one sub in the front, and one sub in the rear. This configuration has created the ultimate PC sonic experience for us, and our lives will never be the same at GD."
I'm ever so close to pushing the "buy" button...