Recently Leonidas, the latest version of Fedora, is released. I have already upgraded my laptop using the latest DVD. However, I was planning to upgrade my office’s desktop directly from internet. Searching internet, I have found a very useful tutorial regarding this. I suggest fedora users to have a look.

http://www.cyberciti.biz/faq/upgrade-fedora-11/

Optionally you can also read this: http://fedoraproject.org/wiki/YumUpgradeFaq