I just got my sexy new 27" iMac and I am loving it. This is the best gaming machine I have ever owned. I also have some pretty kickass Logitech Z-5500 5.1 speakers, however, they don't seem to get recognized as surround sound. The sound setting in Half-Life 2, for example, is stuck on "2 speakers." Is there any way to get true 5.1 surround sound while gaming with this iMac? Would I need an external sound card or something? Would it work if I was gaming in Windows with Boot Camp? Any help is greatly appreciated. Thanks in advance!