Here is a bit of info andy, but beware - you are about to delve into a never ending dark tunnel, lol.
http://www.tech-faq.com/how-do-quad-core-processors-work.html
In essence, at default affinity and priority settings, the newest task is sent to the least utilized core (or cores). When we start changing affinity, we start restricting which cores are available for a particular process during this decision making process. When priority is changed, processes are no longer on a 'first come first serve' basis, the higher priority processes are given a just that, a higher priority.
Obviously, the motherboard plays a HUGE part in this, and determines the overall efficiency of the multi core cpu. Unfortunately, the majority of people buying over the counter have very little, if any, information on the motherboard specs when purchasing.