Ubuntu Natty and Oneiric open the Ubuntu Software Center when you double-click to install any .deb file. As USC is quite resource-intensive, the whole installation process is often very slow. A faster and quicker way is to use the gdebi package to manage your deb file. Type the following command in the terminal:
sudo apt-get install gdebi
Once installed, right-click on any deb file in Nautilus and select Properties. Go to the “Open With” tab and select gdebi as the default application. That’s it. Whenever you double-click to install a deb file, the gdebi package installer will open up instead of Ubuntu Software Center.