Need Mac/Win Compatible External USB Sound Card

[Doctor Suarez]

I have a somewhat unique problem.

I'm switching from a WinXP box to a Mac Pro (for a mix of video editing and gaming), and both of these apps are greatly enhanced by having a good 5.1 audio output solution.

Currently, I have a Logitech 5.1 speaker setup that is already hard-wired into my office. However, to achieve surround sound, it accepts audio inputs in the three-cable Green/Orange/Black setup. The Mac Pro only outputs a single audio cable or an optical out, which doesn't even work for on-the-fly sound that games use.

Therefore, I need a good external USB sound card that will work in both OSX and Win XP, and that can output in the three-cord G/O/B system used by my speakers.

Currently I can only find the Griffin Firewave, which doesn't seem to be Windows compatible, or the Creative SB Live! 24 bit external, which doesn't say whether or not OSX will read it, and is somewhat out of date anyway.

http://us.creative.com/products/product.asp?category=1&subcategory=206&product=10702&nav=technicalSpecifications

Can any of you think of a solution?

Thank you.

PS: I'm a very recent switchie, so be nice.

[bousozoku]

M-Audio sells a few, including sonica, sonica theater, revolution, and audiophile. I'm not sure about the connections you're using, though.

[Doctor Suarez]

I checked... they're all either MIDI-based or internal PCI cards, and since the Mac Pro is PCI Express, they won't connect.

Does anyone have any other ideas?

UPDATE: The Sonica Theater wasn't on their products, page, but it looks like the ticket. THANKS!

So, does anyone have any competing suggestions? Just for variety's sake, I mean.