Wanting to buy a decent pc speakers confused with all the terms used.

I want to get a new set of speakers. But I am confused with all the terms being used. I tried looking it up but I just got confused even more. Can someone in Layman's term help me out?

When looking at a speaker's Wattage for example, Companies use, RMS, P.M.P.O., Average Music Power Output, and Dynamic Output. What do they exactly mean?

What other things should I look into other than the Speaker's Watts rating?

I'm looking into these at the moment:

http://www.thespeakercompany.com/MS516-51-PC-Speaker-System-P13C16.aspx

http://www.bestbuy.com/site/olspage.jsp?skuId=9105443&type=product&id=1218023506854

http://www.amazon.com/Logitech-Speaker-System-Subwoofer-Black/dp/B000AM6QHE

http://www.amazon.com/Logitech-Z-23.../B0002SQ2P2/ref=pd_cp_e_1/192-5493778-3251040

http://www.amazon.com/Harman-SoundSticks-II-Multimedia-Speaker/dp/B0001DBEM4/ref=pd_cp_e_3

 

What do you guys think about this one? It was recommended to me but I don't know anything about Swans.
http://www.theaudioinsider.com/product_info.php/p/swan-m12/products_id/115

Davros, thanks for the link those look good too! it's little more than what I would want to pay but those look awesome!

I am torn between your link and the logitech Z2300s

 

Went ahead with the Cambridge Speakers! Thanks guys for all the input

 

Sorry for the long delay. I forgot to check the thread again. The Cambridge speakers I bought were really nice! It really shines when the volume is at 40% minimum. I am using it for music and I've never heard this type of quality coming from a subwoofer. The Bass is really clean. The construction is pretty solid as well. The only thing I can complain about is that I can't use it to anything more than 25% at the moment because my neighbors complain. (I moved to an apartment.)> I am planning on soundproofing the wall between my neighbor and my flat. It is a major jump in quality to what I was using, which was an An Altec Lansing that i got for 30 bucks.