no. The software has to be specifically written for dual processors. It will work just fine if it isn't, but you won't get the performance increase you'rel looking for if it's not. I'm not sure about Samplitude, but I am pretty sure that Sonar supports dual processors.
On a somewhat related topic... Cubase SX let's you use 2 or more completely diffferent computers. They get linked together through an SPDIF connection. You can use one computer to record on, use another one to run effects, and even a third for a soft synth. All of them stay perfectly in time...supposedly.