It's been too long since any experience with CentOS-4 for me to remember its udev details, so just let me welcome you to the CentOS fora and recommend the reading for new users linked in my signature.
You should be aware that 5.3 is severely obsolete and consequently unsupported, the current CentOS-5 release being 5.7. See the CentOS 5.6 Release Notes
Section 4 for details on the recommended update procedure, and CentOS 5.7 Release Notes
for other information.
Similarly, the current CentOS-4 release is 4.9
, and It is also worthwhile to note that CentOS-4 reaches end of life
in the very near future, so it might be more productive to work on replacing it with a newer release than putting a lot of effort into a dead-end product.