Need Help installing Ubuntu 12.04, This kernel requires PAE.

I tried to install Ubuntu on nearly a decade old laptop and it gives the following message :-

This kernel requires following features not present on the cpu
unable to boot - please use the appropriate kernel for your cpu.

The laptop runs Ubuntu 11.04.

I had no problem installing any O.S on it.

What is PAE?

Is there any version of Ubuntu 12.04 that doesn't require PAE?

I tried searching the problem, but the results are mostly about virtual box.

Thanks in advance.