Dual Processors

[Bop]

Ok, i've been shopping around all over the place for good ways to update my computer, and i talked to a fella at a store who told me dual processors were the way to go--> what do you guys think of these things? how do they work? do they actually make your computer lightening fast? do they help prevent errors? and am i going to have problems running programs on these things? are they really beneficial or was this dude just trying to jip me?

~ thanks