Device driver installation error kernel-devel or kernel-source

I tried to install device-driver (Graphics driver) for Geforce 8800-GT, and during installation, it says that

kernel-devel or kernel-source is not found.

I am using Redhat Enterprise 5 , 32bit version.

When I go to Applications -> Add/remove software …
and when I check the available download list, it only shows

kernel-devel for i686 (64bit ?) version… but no i386 version…

any solutions ?

su
yum install kernel-devel
exit