My RT2000 outputs to external monitor through the firewire ports fine - but if you try to install both Vegas & Matrox/Adobe on the same drive you will have conflicts with capture drivers and the Matrox DV codec. I created a dual boot with Vegas and Matrox on seprate partitions and all works fine.
My next question would be...
Can I take advantage of the Matrox 2500's *real time* processing with Vegas or is the card just supplying output at this point?
No - Matrox only supports Adobe Premiere for there REALTIME functions. You can't even use the break out box unless your in Premiere. Vegas CAN use the firewire ports on the RT2500 to capture and to preview but it's REALTIME funtions are useless while in Vegas!