don't install the tarballs unless you have to. They work fine don't get me wrong, but why do it when you can use a package and the src rpm's are sitting right there? Not to mention you have a package based distro. (it's easier in the long run, trust me) But for some reason the prebuilts for rh8 doesn't seem to be working for everybody, or anybody as far as i can tell. (i tried them once with the same problem you guys have, then i remembered why I never try installing the pre-builts.) src rpm's are your friend as long as the makers did a decent job making the spec file. But if they didn't, whatever they built for your specific distro is just as good as what you woulda made yourself. I guess this does bring up a good reason to sometimes use tarbals when all else fails. Expeically if you have problems with rpm's from places like freshrpms.net where they guy does his best making some other guys spec file. This is not the case with nvidia thou.
Just do it clean and easy. I responded with instructions specific to rh8 here. Maybe this will help?