Respectfully to everyone else here, over on the Matrox forum they are much more knowledgable about this particular card and it's configuration issues.
Don't let the Matrox forum put you off though. You'll likely find a boat-load of config issues fro the card but the thing to remember is... only those few with a problem are actually posting.
Do check your system against their compatible components lists though.
I hope you get sorted soon. It's a great piece of kit and mine has served me really well. Realtime MPEG2 export alone is worth the money.
