Don't understand the question.
There two possible versions of Matrox MGA Millenium G450:
AGP and PCI.
What seems to be the problem?
From what I see:
your's is AGP, you incerted the card in the AGP slot, you installed the right drivers for the AGP version, but
the Win2000 shows you in the Device Manager that the card is in a PCI 0 (or 1, whatewer) slot,
is that right?
What is your computer/motherboard? Does it have an on-board video?
What setting options related to AGP mode or AGP/PCI you can see from the BIOS setup?
Are you sure you installed the right driver? Unfortunatelly the http://www.matrox.com/ is not accessable for me, just to see are there separate drivers they have there for PCI and AGP.