For Fedora to use the ~/.xinitrc, ~/.Xclients files you need to install the xorg-x11-xinit-session package. I found this info hard to find(!) and in some ways I don't know why it isn't installed by default. It is very useful for the likes of Mythdora.
My .Xclients file for my Mythdora 10.21 box contains the following:
/usr/bin/xsetroot -bg black
/usr/bin/xvattr -a XV_COLORKEY -v 66048
/usr/bin/irexec&
/usr/bin/ratpoison&
/usr/bin/mythfrontend
That way I don't get any annoying gnome/kde popups/message balloons and other annoying stuff that's hard to get rid of without using a mouse (in particular when you are only using a remote control!)