[CentOS] recognizing correct number of cores on CPU

I just installed centos 5.5 x86_64 on a new HP laptop.
It has the core i5 processor.

only 1 cpu is detected should be 2.

This has happened before. Is upstream not keeping up with
new processors released and updating the kernel?

I'd rather not go through the process again of putting a newer kernel
on the machine and having something different out there than "stock" centos.

Jerry