Home Cinema System To PC

Hi guys I bought a Targa HC-5100x off a mate last week and I cant hook it up to my pc...Dont know what cables I need and where they go or do I need a soundcard etc.Any help would be appreciated

Here is the sound system here....



http://www.billigdrucker.de/drucker-7793.html

It has Aux In (Red and White)

This is my pc and its connections



Audio: Six back-panel connectors for line-in, line-out, microphone, rear surround, side surround, two front-panel connectors for headphones/microphone, integrated 7.1 channel High Def sound

Its a Dell Vostro 200 Mini Tower...

So can I hook it up without buying a soundcard?

What cables would I need if it can be done without a soundcard...

Thanks