I've installed a new ATI RADEON video card, but UBUNTU won't recognize it.. It had an older ATI card in it to start with. I have tried manually selecting the new driver, but it always returns to the old selection. Any help would be appreciated. Thanks.

Try replugging it and going to system->administration->restricted drivers (something like that) and from their you should be about to choose and install the drivers you need
Hope that's been slightly helpfull

Thanks, but that doesn't do it either. The drivers for the new card are already on the system. I think the problem lies with gnome display manager, but not sure.