I would suggest saving up and switching out your motherboard and CPU. First off, you won't have to bother with switching in the future and having the feeling that purchasing that outdated CPU was a waste of time. Second, nowadays CPUs are much more efficient and will easily consume half (speaking intel of course) the power outdated CPUs will while offering much greater performance as well. The power savings might justify the cost itself.
But if you want a perspective on the qx6700, here is mine. Benchmarks show that at stock, the 6700 is a mere 15 or so percent better than your current processor. Sure you could overclock it a bit and bring that percentage a bit higher but you would have to invest in a, at least, decent CPU cooler which will set you back another 30+ dollars and not to mention, your OEM motherboard will most certainly be quite cheap and won't allow for a very effective overclock (assuming the VRM design is decent enough as to not explode in the process).
Assuming you don't need top of the line power in the future, I would strongly suggest going with AMD if you plan on swapping out your mobo and cpu. AMD is said to remain on the AM3+ standard for a while so no need to swap mobo anytime soon and for 100 or so dollars, a newer AMD processor will wipe the floor with the qx6700. It will be more powerful at stock and will be unlocked. With a decent motherboard (an extra 80-100 dollars tops), you will also be able to push the clock higher and set the qx6700 and whatever AMD CPU you might choose (I would suggest the 6300) even further apart.