I've got a 2nd generation Intel i5 processor with integrated graphics. In live usb mode, Ubuntu uses this one and Unity works fine. After installation with automatical updates and 3rd party software installation, I can't use Unity, and Ubuntu seems to use the nVidia grahpics card. Though Jockey tells me the driver would be activated but not in use.
Right after Login, it tells me I lack 3d support for Compiz. After removing the driver, Unity works again. Even after installing the Nouveau driver it works. I'd be really happy if someone could tell me why that happens and how I'm able to use Unity with the official nVidia driver, because it still is much better than Nouveau.