Quickest way to upgrade Ubuntu Hardy Heron to latest version

"The quickest way to upgrade is to update /etc/apt/sources.list as others have suggested. However, the approved way is to upgrade to Intrepid first, then to Jaunty, following the instructions provided.

Users of Ubuntu 8.10 can upgrade to
Ubuntu 9.04 by a convenient automated
process. Users of older Ubuntu
releases need to upgrade to Ubuntu
8.10 first, and then to 9.04. Complete instructions may be found at
http://www.ubuntu.com/getubuntu/upgrading.

This should reduce the likelihood of having to troubleshoot issues arising from the upgrade."

"Just replace ""hardy"" with ""jaunty"" and do:

apt-get update ; apt-get dist-upgrade -u"