5.1 Sound Card

As above- yes, you need a 5.1 card to get 5.1 surround

and Yes - the one green plug does it all

I'm not sure; but  I think the speakers might still work in a 4.1,4, or 2.0 soundcard, but you wouldn't get the extra channels

bc :-)

You will need a 5.1 soundcard to use them fully.
3 jacks, one for front speaker, one for rear and one for subwoofer i think.

To get true 5.1 you need a 5.1 sound card.

http://www.logitech.com/index.cfm/products/details/US/EN,CRID=2,contentid=5048,detail=2

Thank link shows the tech info from Logitech's site.  It does have an analog stereo jack on it, but that would be a waste of this fine speaker system to hook it up to a run of the mill stereo sound card.

What kind of sound card is in you computer?  Some MBs have 5.1 built in.  You can reconfigure the jacks.  

you will need to use 3 jacks colors can vary but..

jack 1 - controls center/sub.
jack 2 - controls left and right front speakers.
Jack 3 - controls left and right rear speakers.

Agree with goblin072; need to know your System, MB/BIOS info helps to determine sound capabilities if onboard or sound card, etc.  Just had a recent little ShuttleX with onboard sound and 5.1 surround sound supported and sounded good with only 2 speakers, running XP Pro.

well.. i dont know i only have 3 jacks.. i a got a k7n2g motherboard..

so if i have 3 jacks in the back of my computer (red, blue, green) i need another card to give better sound?

Maybe, maybe not. A lot of the 5.1 cards will allow you to run those three connectors in different modes. In Stereo mode, they work "old style" where green is stereo out, and the others are line in and mic in. In surround mode, all three are outputs. It depends on what's in your machine and how you configure it.

The Z680 also has digital inputs. All 5.1 sound cards should have a digital output. You can just connect that directly to the speaker input with one wire and you're done! You just have to have a cable that's compatible... either coaxial or optical, it has to match your sound card and this speaker set.

Apparently we were all talking to ourselves and the Asker either got what was needed and chose not to respond, or didn't know how to close a question.
Thanks for your work here to help cleanup these oldies.
Asta