I am having the same laptop and running 12.04 flawlessly.
turned off NVIDIA GPU and now battery life time is more than 3hr.
I will assume you have a fresh install and have not installed nvidia drivers OR ironhide.
(If you installed ironhide please do a fresh install.This will save time and frustation.)
Instruction for installing Bumblebee to turn off discrete GPU and enable only when required
Type the following in terminal,
sudo add-apt-repository ppa:bumblebee/stable
then
sudo apt-get update
To install Bumblebee using the proprietary nvidia driver:
sudo apt-get install bumblebee bumblebee-nvidia
Run following
sudo usermod -a -G bumblebee $USER
Reboot.
If you just want to disable nvidia card, no need to learn followings
Usage Instruction :
To run a program with nvidia card, use optirun command prefixed in terminal.
Like to run glxspheres with nvidia card type
optirun glxspheres
To run firefox type : optirun firefox &
Note: If you intend to run 32-bit programs like Wine and using Ubuntu 11.10 Oneiric or later, install 32-bit libraries with:
sudo apt-get install virtualgl-libs:i386 libgl1-mesa-glx:i386 libc6:i386
Linked Questions:
How well will Nvidia Optimus cards be supported in 12.04?
How well do laptops with Nvidia Optimus work?
Can't use nvidia card/driver on optimus notebook