Sounds like you need to re-compile your kernel to support dual processors.
Go to http://www.justlinux.com/nhf/Compiling_Kernels
for instructions on how to compile your kernel.
You don't need to down the updates unless your kernel version doesn't have an option of supporting dual processors.
After you are done compiling the kernel, you have to add a line to either LILO or GRUB.
Make sure you keep the original kernel image so you can always refer to it if your re-compile kernel does not work. If the new re-compiled kernel works. Leave the orignal in your computer for a few weeks.