If you've managed to get Powerstrip to work with the Matrox in VGA and it's not working in DVI, one possible cause could be that Windows is only allowing you to set resolutions it 'knows' the device can handle. Somewhere in Display | Properties is often a checkbox marked something like 'show only supported modes", when setting up PS on my old AE300 I needed to un-set that.
Unfortunately, it's an issue with the Panasonic DVI blade. It only accepts a hdmi dvi signal at the moment for the vast majority of resolutions. I think the only other ones that work for me are 1024x768 and 800x600. I have been reading on AVS that there are success stories with people re-flashing the cards but how they do all that is totally beyond me!
HDMI displays are going to put a LOT of HTPCs out of action I fear, I don't see an HDMI-compliant video card any time soon, I think it's possible that the license owners won't allow video cards to support HDMI/HDCP until Palladium is available .. they have nightmares of hi-def DVDs being playable on PCs as it is.
As for flashing firmware, I've flashed DVD drives and BIOS' only in dire need, never touched a graphics card.
Madders: all that person is doing is changing the resolutions that the DVI board reports to windows. I don't know why that is considered necessary, because my board also mis-reports the resolutions back to the PC, but that doesn't stop me setting up other resolutions and driving the display at it's real native res.