I spend most of my day working at my Mac and have moved most of my music into iTunes. Wanting a good speaker system to use with my Mac, I purchased a Cambridge SoundWorks surround sound system designed for computer use. Evidently, I now need a sound card to take full advantage of my new speakers but am unfamiliar with sounds cards. I'm on a G5 running OS 10.3.9 I'd appreciate any advice regarding sound cards for Macs. Thanks! But on second thought, do I even need a sound card?? Although I watch DVDs on my Mac, I bought the speakers to listen to my songs in iTunes. Since the songs do not have separate rear and center channels, I wouldn't need a card that would allow outputs in those channels anyway. Right?