That's by far the best/easiest to understand explanation I've ever seen describing essentially how multiple cores function on a computer. I'm going to start using this explanation, as I know a few people that I still haven't been able to get to fully understand why multiple cores are good.
I guess all it lacks is a mention of intelligence for each calculator guy (MHz/performance)- so fewer guys with higher intelligence may or may not be better than more guys that are each dumber.
Intelligence is probably a bad word to use...finger speed? Since faster processors don't do the same task better, only faster.