ON MY RAM HARDWARE , WHERE SHULD I SEE THE SPEED IN MHZ ?? IS FSB AND RAM SPEED ARE SAME ?? CONFUSED..!!?

IM GOING TO BUY A NEW DDR2 2 GB 800MHZ / I NEVER YET SEEN ON ANY RAM HARDWARE THAT SOMETHING LIKE " RAM SPEED =800MHZ " SO IM CONFUSED .... ON RAM I SAW MANY NUMBERS SOMETHING LIKE .... FSB 800 , IF I SAW FSB 800 /IS IT MEANS RAM SPEED IS 800 MHZ ??? HOW DO I MAKE SURE FROM THE SHOP THE RAM I HAD GOT IS 800MHZ ITSELF ONLY ???