Virtualy all distros have SMP capabilites from the get up and go.
I know suse, mandriva and redhat all have premade SMP kernels which get installed automatically when it detects multiple CPU's during the linux linux, and probably all the other distros do the same.
But anyways, even if your distro does not have an SMP kernel out of the box, you can install the kernel pacakages and compile you own with SMP and other optimsiations specific to your system. eg you have 4 cores/cpus not just 2
A big gotcha might be that you distro's kernel does not know about dual cores(as opposed to 2 CPU's), in that case you will have to look up some tweaks/patches to get working.
*HOWEVER* AMD has posted a dual core linux cpu driver
on their site which may do the job for you.http://www.amd.com/us-en/Proce...chni...1_13118,00.html
good luck, and be patient
PS their is another thread in the troubleshooting section where someone is trying to sort out some dual core problems for suse linux.