I installed Red Hat 9 on my desktop at work -- since I'm the assistant system administrator, I can get away with things like that -- and I wanted to see what my upgrade path would be like with the apt-get/synaptic setup. I loved it so much that I started to experiment with it. I pointed Synaptic toward a bunch of Fedora Core 1 APT repositories instead of to Red Hat 9 APT repositories hoping that it would let me upgrade to Fedora Core 1. After it grinding away, downloading over 600 MB, it appeared that I was met with success. Everything looked like Fedora Core 1, at least, how I thought it should look. I wouldn't really know, having never installed it before. My graphical login said "Fedora Core" on it, and thus I was mostly satisfied . . . until I noticed that my /etc/redhat-release still said "Red Hat 9 (Shrike)" in it. So I ask you, am I really upgraded all the way? Or are crucial things probably missing? Or is it just that file?

That is just a file. apt will upgrade packages for you. As long as you are running the correct kernel, kde, and other app versions from Fedora Core 1 you are essentially using Fedora. I am not sure which package contains the release file from redhat, but you could always remove it if it really bugs you