I think I see where your going, configure/create a config file for each that works than put both cards back in and merge them into one, ammending it to display as one and two.
Don't forget when you have both cards back in to scan the pci so that the config files knows where to look, indase they have changed.
In the link to that how to that I put up it mentioned somthing about the restrictions on the colour display. Both having to be the same of which it must correspond the capacity of the lesser card, that may have something to do with why you recieved the rgb error.
Anyway thanks for the update and most definately post how you go.
Almost forgot, I also came accross this variation with gives virtually gives you a dumb terminal from one box so that you can also add keyboard and mouse etc. http://www.linuxplanet.com/linuxplan...orials/3100/1/
If the dual monitor fails you might try this second one.