>am trying to set my computer up for 5.1 surround monitoring
Sorry Peter
The MXO2 is not a general purpose computer audio device and doesn't identify itself as such to the system. It's drivers support the V-OUT quicktime component and when you're working app's or system tools that use that component then you should have no problems.
It would be a nice value added feature tho ... you should add it to the feature request forum here:
http://forum.matrox.com/mxo/viewforum.php?f=6
Best
Andy