Quad core and Duel core...etc..?

What exactly is the deal? Does quad core actually have 4 CPU's in it? Is a duel core 3.0 GHz actually like 6.0Ghz in speed? So a quad core 1.5 GHz is the same as a duel core 3.0 GHz? Please explain this all if you totally understand it. Also what is the fastest computer out there and what is the max FSB ? (1333.MHz?) Thank you for your help.