What extensions are you using for that card?
I have the 10.6 extensions if you want to try dropping those in? Although you'll still have the same problem as with the Intel GMA graphics, in that you'll have no graphics acceleration.
GeForce7*** Extensions
EDIT: Please wait for the OSXH update and use the kexts that they include. They test everything and the files in my link are raw originals straight from OS X 10.6.0 that I have not tested, as I have no machine to do so.
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No problem.
It involved mounting the Recovery HD, setting rwe permissions for user and modifying all platformsupport.plist's.
I then converted base system.dmg into a read/write image (read only on the recovery partition) and modified the relevant files within there. Once complete, converted the new basesystem.dmg to "compressed" and copied it into the recovery HD (made sure I backed up the original first).
I made sure all permissions were reset and any files that I had unhidden were set back to hidden, then unmounted the Recovery HD.
Rebooted into recovery (using CMD+R) and it all worked perfectly.