Right click on the Matrox PD-SE icon in your task bar. Select 'Matrox GXM set-up' and you will get this image:
As you can see it shows your your type of TH. IF you have a digital TH update the firmware* from here and then install the latest version of PD-SE from here (same version as I am using). Run the set-up Wizard anabling widescreen modes and (after restart) Bob is your mother's brother. If you are using Vista and have a 200 series NV card then try the BETA PD-SE from here if after flash you cannot get 5040x1050- heaps of people (including me) have had problems with the latest NV drivers, Vista and 5040.. AFAIK you cannot flash the analogue version :(
*Make sure to take a firmware back-up AND check the back-up has a size other than 1kb. If it doesn't make a back-up of a few hundred Kb and you attempt to flash the firmware it may stuff your unit...did to mine and others. The best way is to flash the firmware with the unit attached to a PC with NO MATROX software at all installed, I used my wife's laptop :)