I'm about to make the switch from rh9 to fedora too. I can't tell you what I've done (since I haven't done it), but I can tell you what I plan on doing in a "monkey trainable"-way.
1. I will download the iso images and burn them to CDs 2. I will reboot the computer with CD 1 in the drive. 3. I will click "next" at all prompts except for the screen that asks me if I want to update my current operating system (which it should recognize as RH9) or do a fresh install of Fedora. At that particular prompt, I will select "Upgrade" and THEN press "next". 4. I will press "next" for all prompts after that point.
-Tim