Connecting 360 to monitor/pc

Ok well i want to connect my pc to my Dell 21" widescreen monitor

http://www.digitalbackspin.com/cms/articlefiles/2452-2007WFP_connector.jpg

As you can see i can connect the VGA cable to my monitor but where do these other two wires connect to so i can obtain the sound (red and white wires)

http://punchbutton.beloblog.com/archives/images/1206/xbox%20360%20vga%20cable.jpg

I have a T7900 creative speaker system, this is the picture of the subwoofer were the wires are connected.

http://jgiam.com/images/creative/015.jpg

Now all these slots have been taken up the bottom 7 by the 7 speakers, and the top 4 by this wire which connects to my desktop.

So can somebody help me and explain how when i get the VGA cable do i connect the red and white wires to my speaker system or my monitor to obtain the sound. Help is appreciated.

Thanks.

Isnt that were u plug the red and white wires and then you plug that into your soundcard?

My speaker system has 4 inputs and i cant see where i can put the red+ white wires in, and the jack would simply make it into one plug and where would i plug that into?