Isn't the echo indigo only two-channel stereo? Excellent sound quality of course, but it'd make it tough to have a nice surround sound system. But then you already will have an S/PDIF digital output on the laptop that should provide great sound and pass DD5.1 or DTS through.
As for speakers, I have one of the Monsoon sets.. though the model escapes me right now. I think I have the MH-505. Personally, I personally prefer them over Klipsch. I'm not fond of the Klipsch ones for some reason. I think they put out too much upper-midrange sound for my tastes while I prefer much smoother sound. I haven't listened to their newest models yet, though.
The Monsoon speakers do have one major thing to consider. They are VERY directional and have an extremely narrow "sweet spot" for listening. For me they work fine since I'm the only one listening and am at my computer when I do listen to them and I like the sound from true flat panel speakers. Oh.. I do feel that the subwoofer that came with them isn't too good, but I don't use it much. It's connected, but I also have a full-size sub similar to the one in my home theater connected.
I also really like the logitech speakers as someone else above mentioned.
All that said.. if money and space truly weren't restrictions at all for me, I would skip over computer speakers a spend a couple thousand or so for a home theater style setup. ($500 receiver, $500 subwoofer, $1000 on speakers and cable). That's unrealistic in the majority of situations though.
My opinions anyway..