I have an imac with an nVidia geoforce 5200 video chipset. I thought that Aperture supported this video chip set, but when I try to start Aperture, it says that the chip set is not supported. On closer inspection, I see that the supported chipset is the nVidia geoforce 5200 "ultra". Are these really different chip sets? If so, is my only course to upgrade the chip set?