In all honesty, i would not recommend any of the multimedia speakers(logitec or any other of the computer peripheral brands) for music or...pretty much anything other than gaming. they simply lack the fatures and quality of the specialist brands. for example i have not seen a multimedia speaker system with an active crossover in the sub (although i am sure there is plenty), this is REALLY important. if you watch a movie you need to set the crossover really low (so you do not get the voices played through the sub).
as you said you like your music clear and loud, some of the multimedia systems have a THD (total harmonic distortion) as high as 3-5% (a really good amp would have 0.05% at the same volume) at a volume that would be considered "loud". sure it will be as "loud" as a much more expensive brand name system but it will sound absolutley awfull. sound systems are much the same as PSUs (for lack of a better example

) in that you pretty much get what you pay for and a "550W non brand name will be weaker than a 350W antec as i found out a few days ago

). as far as sound quality goes you will get a much better frequency response from a good set of hifi speakers than you will get from a full 5.1 surround setup for $500.
my recommendation: if you only plan to use the speakers for gaming logitec will be great. however for "loud and clear" music i would stay away from them i would go for a nice 5.1 hifi amp from yamaha (or any other reputable brand) and even if you can only afford two speakers to go with it (get some good hifi speakers). you can always upgrade in the future by simply buying some more speakers, this is another advantage or buying a hifi system is that you can upgrade as you go.
I hope this helped, if you have any further questions feel free to ask