Anyone care to help me find the Matrox Powerdesk software for download?
The Matrox PowerDesk is part of the DTH2G software package. You just download the one for Win 7 x64 (your OS) here:
Install it and you will see the Powerdesk.
This should work as a guy with Nvidia Surround reported a success (top post, point #3):
Alternatively, you can wait a few months as Nvidia rep is saying that they are working on a solution and should be ready early this year.
I hope this helps.