Usually on the palm rest on a laptop, flanking the mouse pad. Also, there should be a more detailed model number on the system. I read a couple of reviews that suggested the laptop ships with an nVidia graphics card on at least two models.
Also, Dell systems ship with a service tag, usually located on the bottom of the laptop. I do have a Dell support account. If you want to send me a PM with your service tag number, I can look it up on the support site and see the configuration it shipped with.
Flynn