If you are unable to use the kernel-devel tools after a fresh install of FC5 , then it seems to be that you may be installing FC5 using the CD ISOs that has a known bug in them in which the i386 CDs are incomplete and are missing 22 packages.
The 5 install CDs contain 2185 packages and the DVD i386 version contains 2207 packages.
Most of the missing packages are related to the kernel-devel packages.
The only workaround is to do a online package update using one of the yum Gui applications like yumex to install the kernel-devel packages.
Here is the bugzilla report about the i386 ISO CDs with the missing packages.
https://bugzilla.redhat.com/bugzilla....cgi?id=186202