There was an article a while back in the main page about memory bandwidth vs clockspeed. According to the article you will get a better performance out of an increase in clockspeed vs an increase in memory bandwidth (which is what a higher FSB would give you). If you are not going to OC then get the 800MHz FSB chips. If you are then get the 533MHz chip.
BTW, I noticed you are planning on getting an Intel made board. If you are going to OC, I would suggest against that as Intel offers very, if any, limited OCing options. I would get the Abit IC7 if you are going to OC.