What CentOS Linux kernel available?

I try to upgrade the kernel for my CentOS 5.4. I try to run yum upgrade kernel-smp and return no result. Eventually, find out this is changed in CentOS 5. There is no more kernel-smp. The following info is found in CentOS wiki page. So I run

"yum upgrade kernel" for my 64 bits dual processor laptop.

CentOS 5 provides the following kernel packages:

kernel: Contains the 'normal' kernel. This kernel includes support for both UP and SMP machines.

kernel-PAE (x86-only): Contains a kernel with support for 64GB of memory on x86 systems through Physical Address Extensions (PAE). Only x86 CPUs that support PAE can run this kernel. This kernel is provided because x86 systems can't address more than 4GB of memory without PAE extensions.

kernel-xen: Contains a Linux kernel that runs on the Xen hypervisor, for both privileged (dom0) and unprivileged (domU) domains. The Xen kernel is compiled with PAE support.

Reference page: http://wiki.centos.org/FAQ/CentOS5