Depends on if the X4 965 provides you with enough performance at this point in time.
My Q9450 is basically equivalent to the X4 965 and I find that the performance is still adequate enough that I am not going to upgrade until Haswell is released. Ivy Bridge will be a significant upgrade. Assuming the same clockspeed, Ivy Bridge CPUs provide on average 29% better performance than the Phenom II X4 and Core 2 Duo / Quad series.
Haswell's performance is unknown. 10% over Ivy Bridge is a safe assumption, but some believe it was be as high as 25% better... I wouldn't hold my breath on that one.