Hi, im having trouble with my Regent Home Theater System Surround Sound speakers Model HT-391. The problem is, i am trying to hook it to my computer, but when i do, it makes this long background noise like (buzzzzzzzzzzzzzzzz) and when i play music, it doesnt come out straight. Also, the subwolfers doesnt work when i pluged it in my computer. Now, when i plug it in to my Ipod, everything works fine. Do i need some sort of sound card or software?