You should have installed a file named: kernel-source-2.4.20-28.8.i386.src.rpm
This has the correct sources for your current kernel, please verify you are using the kernel you think you're using: uname -r
You can avoid the hassle of the compilation if you go get an RPM for the driver, which you can find here: http://atrpms.physik.fu-berlin.de/di...idia-graphics/
The kernel driver name problem may be fixed by cleaning out the kernel source and setting it back to a good known condition. As root run these commands:
mv .config config
mv config .config
This should clean things up, then try the driver build again.