nvidia 6600 working but not recognized

This one has me completely stumped. A clean install of RC1. Upon loading,
it lets me set the correct default resolution for my LCD monitor (1280x1024,
at 32-bit color). Everything (except Aero) displays correctly. But my
nvidia 6600 AGP card, which is driving the display, is nowhere recognized.
There is no "Display Adaptor" listed in Device Manager. When I access
"Display Settings," I get "Default monitor on [blank]," although it seems
perfectly happy to let me set even higher resolutions that my monitor
wouldn't support. When I click on "advanced settings," and "adapter
settings"--"properties," I get a "VgaSave", something generic and not useful.
And when I attempt to load the nvidia beta drivers for RC1, it shuts down
with "no drivers compatable with current hardware." And yet the monitor is
clearly running through the nvidia card, and at pretty a pretty decent
resolution.
Thoughts? Thanks