Ah, the joys of video editing! It mostly sucks. OOPS! Forget I said that. Even if it is true. If I had to make a suggestion, I would vote for Canopus hardware. Guardedly.
Canopus had a well-deserved reputation in the industry for buggy software and excessively processor-intensive products until the last couple of years. If you are doing DV, I would look at the DVRaptor2. It has an on-board processor and can do most rendering tasks in real time. About $500 US.

I used to like Pinnacle Systems hardware lots, but the last 3 years or so have seen their tech support turn to crap, and their software is awful. As for Matrox, I'm not sure right now. They have had distributor trouble over the last few years due to their warranty and return policies. These days, I would focus more on overall system performance ( quick CPU, plent of good RAM, a good high capacity hard drive [SCSI not required]) and not worry about specific video hardware. But, in any event, your video card will not affect your rendering performance in the least unless it incorporates video rendering hardware so do some Matrox products