I thought I'd answer my own question about the matrox card. http://forum.matrox.com/mga/viewtopic.php?t=19691&;
Has anyone gotten the latest xorg7 working with dual head matrox drivers?
Still wondering about how to get the older -dev packages, because it would be nice to know how to do it, but at least now I know I can upgrade to xorg 7 :-)