To facilitate the installation of ROS (especially when a reliable Internet connection is not available), we created an Ubuntu image with ROS pre-installed, with which you can install both Ubuntu and ROS in one go. It is based on ros-indigo-desktop-full, with essential environment variables set up. After installation, you can still download and install any ROS packages you need.
If you want to give it a try, please follow the link here: ubuntu-ros-indigo-v1.0.rar.