Fedora 12 and later use ext4 as the default filesystem, so you won't get that if you try to upgrade. A full wipe and re-install is best from F8.
There is no Fedora "Core" since FC6
, it is simply Fedora now.
If you were determined to upgrade instead of a fresh install, you could try adding the option "upgradeany" to the kernel boot options when booting from the install dvd.
Otherwise, have you considered Mythdora
? Currently based on F12 it is a complete Fedora / MythTV set up with updates and everything included.