The one thing I would change is to put the AMR slot between the AGP slot and the first PCI slot. That way there would be lots of room for the heatsink/fan on the video card. As it is you may not be able to use the first PCI slot if you have a fan on your AGP card. And from what I've heard the Matrox cards run hot, so need it.
I wonder if it's too late to make such a small change.