The newer FSBs are faster, so a 266 is faster than a 200, then they had the 333 then the 400 and now as you said the 800.
Each is a new development along with faster CPUs and RAM.
The higher the FSB then the faster the PC is but to get the best performance then it needs the same speed RAM and the CPU to be compatable, unfortunately todays fastest thing is very expensive and is tomorrows has been.
If you try and keep up with the newest developments then you need to have very deep pockets
:good: A simple explanation of what it is would be :- The oscillator speed that is used for your "cards", memory ect. It is then multiplied up to your processor speed. ie an 800fsb with a 3X multiplier would give would give you a 2.4gig machine.
But as Sandra said, there is more to it than that.
I am told that the best balance between cost & performance @ the moment is to build a 2.4gig but make sure the pro'r has the "widest bus" available
& the latest multi threading.
This is only an opinion!. Do as you are & research for your self before doing anything. Find the balance that suits your pocket.