Dell Inspiron 7000 Series - Changing the Display Adapter?

So I was hoping to be able to add a second monitor with my Dell Inspiron, but I didn't have an extra monitor just lying around, so I was hoping to be able to use my old laptop for the same purpose. I tried hooking up the two computers with an HDMI cable, but there was no response. I'm fairly certain that the issue lies in the Inspiron's Display Adapter, which uses the Intel graphics card instead of the Nvidia one that is also installed. Is there some way to change the display adapter that the computer uses?

Or, if I'm just completely wrong about what's causing my problem, is there something else that could be making it so that my two laptops won't connect via HDMI?