Upgrading my CentOS kernel

[tmcallaghan-Re5JQEeQqe8AvxtiuMwx3w at public.gmane.org (Tim Callaghan)]

I'm running CentOS 5.3 on a VM and I need to upgrade the kernel to
something newer for testing purposes.

Having never done this before can anyone point me in the right
direction (a good step by step tutorial would be awesome)?  The CentOS
wiki only seems to have instructions on how to customize the CentOS
kernels, not to run a more recent kernel.

Thanks.

-Tim