First of all, you don't need to look for an Intel driver around, because it is shipped with Ubuntu and installed by default.
There is a bug with the Intel driver and the card you're mentioning (I have the same card), however most reporter have it with their laptop LCD, not the external screen. I also have no problem with external screens...
Anyway, there is a workaround for this bug that works for the LCD internal screen of the laptop, perhaps it is working also for an external LCD, you could give it a try.
Check the following bug report: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/538648
The workaround concerns adding
i915.powersave=0 to the kernel parameters, see the [workaround] section in the bug description.