PC + Klipsch Promedia Ultra 5.1 + MP3

I am very new to this whole music-tech stuff. I am interested in setting up the Klipsch Promedia Ultra 5.1 speaker system with a PC and an MP3 player (interchanging the MP3 and laptop). My problem is that I do not know if the 5.1 system would be supported by the computer I am purchasing. And also, would the MP3 player support the speaker system, as well? I hear that some channels dont work in either of these cases but I am not sure to the validity of these remarks. Bottomline- I want all of the speakers and sub to work with both the laptop and the MP3 player. How can this be done?

equipment that I would be using includes....

laptop- unsure of which sound card will be in it
Promedia Ultra 5.1 speaker system
MP3 player- Cowon iAudio M3

5.1 channel speakers are designed for use with...you guessed it...5.1 audio sources, such as DVD. MP3 are regular 2 channel stereo and there is no use for the extra 3 speakers since nothing is there in the first place.

wait, so would a Xitel Pro hi-fi link or a Soundblaster Extigy make it possible for the laptop to use all of the speakers? if so, i'd imagine that the MP3 player could also be hooked up to it as well because the connection would be the exact same as the laptop?

Nope, not unless they have an all channel stereo feature. You only need the 2.1 system if you're just listening to music.

The Extigy supports 5.1. in the menu for Soundblaster you can set the speaker setting for 2,4,5.1 and headphones. The anolog jacks on the back are input/output/headphones/speaker/speaker. You would simply plug the mp3 player, using a stereo mini-plug jack into the input port. But the soundcard whether internal or external has to be connected to a computer.
From what I understand the PC speaker system is designed for this, however I am not entirely sure how they hook up. From what I know you send the signal to the PC speaker system. The sub in that systems powers all the speakers.
I have my soundcard signal using the output jack going to my receiver which serves as the processor, bypassing the receivers processor.
Hope this helps.

A question about external soundcards? Do the soundblaster extigy and audigy (the 2.0 usb one that im not sure of the name) serve the same purpose? The xitel pro hi-fi is as well? if so, any recommendations from anyone about these products? thanks for all input
-brendan