Now is the best time to upgrade, and upgrading is a breeze, sit back relax, and issue the following commands!
Upgrade from 7.10 to 8.04 LTS
Press Alt-F2 and type update-manager -d
Click the Check button to check for new updates.
A message will appear informing you of the availability of the new release.
Follow the on-screen instructions.
Command line upgrade:
sudo apt-get update && sudo apt-get dist-upgrade
Download the iso: