The HD500 5.1ch speaker packages are good for the price, and actually make excellent computer "gaming" and video-watching speakers, as well as "decent" music speakers. They are far and away better than anything labeled as a "computer speaker" outside of the likes of M-Audio (I have a pair of M Audio BX5 D2's running off a Fiio E17, sound card being an Asus Xonar Essence STX).
If you want good computer surround, these are as good as you'll find until you hit about twice the price, especially considering this includes not only the five speakers but also the subwoofer.
They are ideal for smaller rooms (I would say no bigger than ~15'x15' or thereabout), such as bedrooms, dorm rooms, and so forth; they will not be adequate for a home theater, a living room, or other big areas.
One alternative is to use the five included speakers as the surround components in a 7.1/7.2/9.1/9.2/11.1-4ch surround sound setup, with some true Towers for Front-Left/Right and a better center. I usually recommend sticking with the same manufacturer so as to keep the sound (the "voice") consistent between speakers, as it can sometimes be very noticeable and very distracting if you don't.
Some excellent front towers to turn this into a 7.1ch setup would be the Klipsch Icon WF-35's: powerful, excellent dynamic range, strong mid-range, and beautiful to look at too ;)
The problem is that the included center channel here is not so great, and I would personally upgrade to a WC-24(W) Center to have a matching voice to the FR/FL towers.
You can then grab a second one of the included center channel speakers, get a pair of wall mounts, turn them vertical and use them as either Front-High/Wide or even as the Primary Surround Channels depending on whether you're using a 7.x, 9.x, or 11.x receiver.