Ive just had the same problem with a toshiba laptop and FC5
i installed by running linux text at the boot cd prompt
when os installed you should be greeted with just a shell, do a full yum upgrade, the install the linva repository rpm
rpm -ivh
http://rpm.livna.org/livna-release-5.rpm
then
yum install xorg-x11-drv-fglrx
then type
startx
you may want to then change your /etc/inittab to give a default run level of 5 afterwards to stop having to manually starting x on ervery boot