Well.. I'm not aware of that P43 mobo which is available at barclays,you may checkout some reviews. I'm having a Foxconn G33M mobo, FSB:RAM ratio can be changed by changing RAM speed (1:1,5:6).
FSB 400 - No sweat, With a bit of tweaking can be taken to 425. This is with an 8X multi (E6750), so...