So you are upgrading to get a faster GPU and CPU----yet you will then hobble your self with a memory transfer bus that is 2100/3200 or 65% as fast as it could be. Actually it won't hurt you at all if the bottleneck is somewhere else---but depending on the application--you may be wasting money upgrading.
But before you do it---I would want to reseach what is slowing down my apps---and you can cover a multitude of slow memory transfer bus problems with a really big L2 cache on the CPU--as long as you are not perpetually reloading said cache---again application specific.
But if you do need that quick main memory transfer bus---you should be looking at a board that takes DDR2 memory.