Better sound system for Mac?

[sphoenix]

I just got myself a fairly simple Logitech 5.1 sound system, which comes with about 5 audio cables similar to this:

My query is, how can I use this system for all sound speakers (front left, front right, etc.) because currently the Mac only has an available port for the green audio, so only two speakers can be heard. Any ideas?

 

[Tomorrow]

The sound port on a Mac doubles as an optical (mini-TOSLINK) port for digital sound. You would need either a set of digital speakers or a digital receiver.

Check out Logitech's Z-5500's for an example.