2.1 or 2.0 setup of PC

The Swans are a very decent choice. It is a really good brand and usually means quality. I have not heard the Swan M10's though.
I currently have the Logitech Z5500 because I wanted 5.1 without having to add a receiver, and for PC only speakers, I personally think they sound better then any others I have heard, including the pro-media's. Don't go for the 2300's though, they are wimps for audio, they go loud but have distortion very early and clarity is only sub-par.

I would not go for the Harmon Kardon, they are better known for electronic audio parts then for speakers.

The Berhringer's seem very interesting but I have not heard them either. The specs sure seem impressive for the price though. (amazon has them for $130 now)

The Audioengines seem like a great speaker but are the most expensive and most impressive of your list. I would pick these over any others with the Berhringer's pulling in second and the Swans as a close third.

As for the other part of your question, music, depending on what kind you listen to can go as low as the hardest hitting movie. If you typically listen to jazz, and rock you don't need a subwoofer if your speakers can go into the 50-60's range without distortion. If you listen to techno/house or R&B or Rap, then you would benefit from a subwoofer greatly.

On a side-note. The Klipsch pro-media speakers pre-2006 were really good. I am not sure what the changed but there is an audiable difference in the newer ones. And for the worse, IMHO. If you could ever get a hold of a new or gently used Pro-Media 5.1, jump on it right away.

The reasoning behind picking the Audioengine's over the Behringer's is due to the fact that 1 is that the Behringer's are studio monitors while the Audioengines are multi-media speakers.
In most cases monitor speakers usually have a flatter, but truer sound. While multi-media speakers will add a bit of their own color to the sound. In this price range, I think the monitor speakers will have too flat of a sound and make your music sound dull. The low end is not everything when it comes to music so the 15hz difference should not be much of a difference, depending on your music choice of course.

The Swans are 5-20watts of power for the speakers and the sub is 40watts. I am not sure where you get the 8watts from.
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I am listening to some Dave Matthews/Tim Reynolds Live At Luther College right now on my Klipsch Promedia 2.1's and they sound pretty good to me. I am in the same situation you are. I want some speakers for my PC at work but don't want to spend a lot. I guess I have been spoiled by my Promedias at home. They are not my reference system, but they work great for listening to a wide variety of music at the PC. I can only speak for the speakers I have heard, but I definately like the sound of these (Klipsch)better than the any of the Logitech's (including the Z2300's), Harmon Kardon's, Bose (even that expensive 2.1 system), and most Altec Lansing's (haven't heard those MX6021 Expressionist, but they look like they would rock!). Funny thing is, a co-worked has some old Altec 2.1 system, that came with an older Dell, that rock's pretty good. Would love to get them off him. I would love to hear how the MAudio's and Swan's sound as 2.0 compared to my Promedia's 2.1. From the reviews I have read, they would both be great systems. I guess I am afraid to buy them without comparing them to what I have. For the same cost I could just buy another set of speakers I know I like. I would give the Promedia's a listen. They can get plenty loud without distorting and have good sounding highs and mids for what the are. I balance the sub and it give these a real nice full sound in my computer room. BTW, I bought them at Best Buy about 4 years ago for $89.00 or $99.00 I think. They were on sale after Christmas. Good Luck.

akalmand - I think that you are on the right track. The cnet reviewers seem to prefer noticeable deep bass and don't really appreciate quality midrange. That may be great for the gamers but not the right direction when you are looking for supple and detailed mids - for me one of the most important aspects when I audition speakers.

I am a little leary of the A2s even though they have gotten many good reviews. S Guttenberg who was a huge fan in his review was startled by how much better the passive P4s sound. Sure they are more expensive but it makes me lose faith a bit. I prefer a neutral speaker and I think you can find good choices in your price range but the A2 is not neutral and many buyers have reported their disappointment. I think that I would like a little large driver. But I have not heard them personally so....

My personal opinion is if you are planning to listen at your desk, skip the sub. If you are filling the room, perhaps get a sub, with speakers in this size. Where you place your speakers has a huge impact on how they sound, including how low. Proper sub placement and crossover from the satellites is very important but many guys just set the sub where it fits and make sure that they can hear it - not a recipe for great music presentation.

Sometimes I find the specs on speakers difficult to believe. It would be great if you could get the speakers into your place and let your ears decide - return the losers, keep the winner. I respect raistline's preferences - mine are similar but different. I would go for the Swans D1080MKII or perhaps the Behringers and skip the sub. Then maybe I would try the A2s. The M-Audios are probably fine - haven't heard them - but I confess an unjustified bias against them (I don't think of them as a speaker company so much). I think the Swan M10 is your best choice if you want a sub.

FYI. I just bought the Audioengine A2's and they are horrible. Way too much bass bloat and muddy mids. The highs are very subdued and everything sounds boxed in. I honestly cannot see how these things get good reviews.

My 10yr old Altec Lansing setup sounded better.

I'm currently looking at some Swans, but as I understand it, TheAudioInsider.com will be getting in some new models and better choices in the next month or two.

I use a pair of PSB Alpha A/V's along with a Yamaha receiver that I picked up used quite cheaply. I had the Klipsch ProMedia 4.1's which seemed okay (for pc speakers that is) until they developed some problems (amp ? x-over ?) and quit working...my friends are now making a knocking sound like someone is rapping at her door, and yet another friend had a set where the volume pot flaked out, and the cost to fix it was insane (comparatively speaking).

For less than $100 I got a receiver + a 5.0 PSB speaker combo, and a toslink cable from Monoprice. The PSB/Yamaha combo (2.0 only) absolutley destroys the Klipsch ProMedia 4.1 set I had in terms of sound quality, and flexibility (volume is close but I think Klipsch wins that one). I can add more speakers and a sub if I had room, or felt the need to.

You should consider checking out used goods in your area (Salvation Army, Craigslist, Kijiji etc.) for good deals. A lot of folks where I live are selling 5.1 receivers with no HDMI for insanely cheap prices because they think they need (or just want) HDMI connectors on their receivers. This means there are good deals to be had for folks like me .

Cheers,

THC