You need t decide what u want t do wit t PC. But unless you will b running your PC at max load for really long periods (eg 3d rendering), you r doing mission critical stuff (eg financial data calc) or u really need the sort of CPU power that can only b got from a dual chip setup (eg 3d rendering, again), you're probably better of with an i7, or i5, etc.
Btw u can overclock Xeons, if u hav t right mobo, etc, but not in t same way as u can K-series i7s etc, n they're not designed for it like t K-series chips