Return Material Authorization, I've usually seem it as.
(It means that the maker has authorized you to return a possibly defective product for inspection.)
If you're getting graphics when the monitor is connected to the graphics card, then the graphic card is working. It sounds like it's running with the generic (VGA) drivers
AGP cards may be a little dicey with Windows 7. As your PC is from 2004, apparently, a little struggle may be expected. Good luck.
I suppose that you have something other than a 5450 (3450, perhaps?) as I doubt that there's a 5XXX card in AGP.
Have you tried these drivers? AMD Catalyst