I still don't see the need though. Since both are Nehalem chips (assuming we are talking about the Nehalem-based Xeons), surely i7 is sufficient for any desktop application? Why go for a Xeon?
I bought the Xeon simply because it was the only way to get ECC memory support. Memory is the ONLY component in most desktop computers that has NO error checking of any kind. That's not good enough for me, particularly since I've been stung by intermittent memory problems in the past.