I'm totally clueless when it comes to all things audio so any help greatly appreciated.

I have a set of Creative P5800 attached to my PC. They have front, rear and center inputs which are connected to my motherboards onboard soundcard.

I was wondering if there was any way of hooking these up to my Xbox 360 and getting surround sound?

I found this but I dont think my speakers have the Toslink input descriped.

Anyone have any ideas? (preferably ones that dont cost a lot )

I don't think its possible. Xbox 360 was/is designed to work with the optical out for the surrount sound, and unless you use something with a digital decoder, (say, your medium range a/v receiver for a home theater) then I don't think there is any way to use the surround sound.