Can you use multiple video cards at once different brands?

i have a onboard video card/graphicks navidia and i want dual monitors so i have a ati rage xl for pci and a trident video accelerator they both work when i set one to primary but never at the same time and i don't have the 1 and 2 screens in the settings when i right click HELPS PLZ|||No, this is not possible, you can only have Onboard video or extended video in use at once. If you want dual monitors, you will need to purchase a graphics card that supports dual monitors.