[CentOS] Upgrade

I am currently running CentOS 4.5 (which, through many Yum updates) now appears to be CentOD 4.8.

4.8 is still rather old, but I havbe lots of stuff (files and stuff installed). I would like to install Fedora but I am worried about losing
all the stuff I have. I would have to back everything up, uninstall/reinstall
things, etc. I am wondering whether there is some way to upgrade to Fedora 
from CentOS without just having to reinstall everything?

- Done.