I am also going to suggest that the Creative external boxes like
will also work with Apple Macintosh gear through the USB port.
Years ago I got an Onkyo USB audio box that did not indicate Mac Support, but as it turns out, the hardware actually works plug'n'play, but the accompanying applications disc was Windows-only, hence no "MacOS" logo on the box. The same thing happened with a analog-digital video bridge (Dazzle Hollywood) I got to grab analog video from a VHS player (using FireWire)... It just works, even though the box had no information on Macs (again, the accompanying software and drivers - which I did not and could not use on the Mac was Windows-only).
Personally, I'd be taking a serious look at that Griffin box (using FireWire)... It is a bit pricey, though...
Please let us know how it all works out...