Probably depends on how much you want to spend. Core7i will blow everything out of the water, even entry-level Xeons, I believe.... The boards and CPUs are expensive - but you can add a lot of RAM (six sockets instead of four).
OK thanks - from what i have just read about the Core i7 i dont think i'll be going that route as they seem $$ and not many mobo's available.
will keep looking
thanks