Please help with G450 and Biostar M7NCD

My G450 is not detected on my new homebuilt computer - Biostar Nforce2
board, Athlon XP1700+, running Windows XP Pro. I had an old Nvidia
card in there that worked fine, but the computer will not recognize
the G450. I've tried two G450s, the result is the same - cannot be
found. When I add the card manually, the Matrox driver s/w still will
not detect the card, even though the "G400/450" is listed in the
device manager. When I run the s/w from the setup icon, I get a
message that says "This software does not detect any Matrox hardware
installed on your computer . . . " When I try to add the card with
the h/w wizard, XP cannot find the drivers in the folder, although
they are clearly there. Obviously, as far as this pc is concerned,
there simply is not a G450 in that AGP slot. I've uninstalled,
reinstalled, tried Win certified drivers, latest drivers, installing
from CD, from hard drive, zipped, unzipped (the Mgafold folder), etc.
Does anyone here have a suggestion?
Thank you very much for any input.

jakesnake