So if I have 4 applications running at the same time, they all will use the first processor until it is maxed out?
Oh no, the operating system will do the best it can to share the load among the available cores. Two single-threaded computing loops can execute independently at almost 'full speed' in a dual-core machine. I say 'almost' because while they run in independent processors, they still have to compete for other system resources.
I wonder what kind of performance I would get with a mobo that allows duel processors for these duel core babies? Imagine, a computer with two duel-core processors! Then again, if nothing takes advantage of this, whats the point, eh?