definitly
just because you have a fast processor speed, doesnt mean the rest of your system wont need a \'bit extra\' and if you clock the fsb, then the gains you will get will far outweigh the gains made by increasing your cpu speed even more....
fo instance, if you can clock your fsb by 15% then that gain will get devided down your pci bus so that your cards all run slightly quicker aswell. this could cause problems if your cards are old and sucky, but if they arent then you should see a great increase in performance by overclocking
get hold of a copy of a benchmarking program like sisoft sandra whilst you do your testing....