There is one important question you should consider, Frodo: What kind of audio are you going to be listening to through your computer?
For gaming, popular music and movies a good set of multimedia speakers like the Z-560's will work fine. Using home audio components can give better sound quality, there is no question about that. But to get to the level where you have a clear improvement over a good set of multimedia speakers requires spending a lot more money. (You'll spend three times the price of the 560's just for an entry-level "home theater in a box" system from Sony or Bose. Buying good individual components can double that in a hurry.)
But if you listen to a lot of high-definition music like classical and jazz through your computer, you might want to consider doing the homework and building a PC audio system from home stereo pieces. For this application you can get better results than nearly all PC speaker systems without spending a lot more money.
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