I have the same laptop, your Nvidia card is called "Optimus" and won't run with the normal Nvidia drivers as Nvidia have "no plans to support it in Linux"
However:
There is a guide on this site:
Installing Bumblebee for Nvidia Optimus
Don't be alarmed by the name, it tells you how to set up the Optimus card and how to increase battery life by appx. 60% in my experience.
You will need to remove the Nvidia drivers you have first - Google is your friend for that.
After that you need to splash the cash on a mini DP to VGA adaptor (8-15 British Pounds on Ebay) for your external monitor as there is currently no support for HDMI and Optimus on the Dell L502x at least (others maybe?).
I work using projectors all the time and find this to be a robust and usually stable solution.
This gives me 1366x768 on the laptop and 1080x1920 on my external monitor.
Hope this helps.
Richard.
Note: According to Nvidia website, your video card has been supported since 295.53
http://www.nvidia.com/object/linux-display-amd64-295.53-driver
Added support for the following GPUs:
GeForce GT 610
:
Be slightly conservative. You may want a later version (to better support your device), but do not want to be bleeding edge.
Unless you want to always download and compile (every OS update), use one of the provided PPAs.
See: Update nvidia drivers with xorg-edgers ppa
Use @robblue2x's method, and try 340.58
Note: 331 is only 331.104 (not 311.113); and 346.nnn is very latest.
Best Answer
Most likely but check here to make sure. http://www.ubuntu.com/certification/catalog