I just bought a 2.1ch speaker system for my computer. In my sound control panel on Vista there is no option for 2.1, only 2ch, 5.1ch, and 7.1ch. What, if anything, can I do so that I can be able to control; the sub from the computer. The speakers I bought are Philips SPA2360/17 2.1 Multimedia Speakers. Thanks in advance.