Bad idea: upgrading your system from Fedora Core 4 to Fedora Core 6 using nothing but the online updater (“yum”). In theory, this is supposed to work. In practice, not so much.
Bad idea: upgrading your broken system from Fedora Core 4-ish to Fedora Core 6 using scratched CDs and/or a drive that thinks perfectly fine CDs are scratched and halts half-way through
Bad idea: Burning a brand new Fedora Core 6 DVD to upgrade your half-Fedora-Core 4-ish-half-Fedora-Core-6 system to a full Fedora Core 6 system.
Best idea: deciding long ago that the /home directory should be on a different drive, reformatting the root filesystem, leaving the /home filesystem intact, and installing a fresh Fedora Core 6, a fresh set of ARM and PPC cross-compilers, and whatever else that might have gotten wiped away. With this scenario, I didn’t even have to reinstall my Firefox add-ons since they’re safely stored in my home directory.
Of course, because of all of this, lost about a half-day of time on Friday and a half-day today, while waiting for percentage bars and crossing my fingers and such. I can do some things on my laptop, but there are still a number of things I can’t do there because I don’t have trusted OS X versions of the tools.