5.1 surround music not working properly..

Okay... I have been using this acer extensa 5630 laptop for about 2years & today only i bought a creative 5.1 t6100 surround music system for da laptop.. All this time i thought it had da sound card but no when i plugged in, only 2speakers working.. Can somebody suggest me what to do??? i tried googling but da answers are freaking me out.. I'm using vista 32bit in my lap.. Help plz..