E6600 or Q6600?

i have a E660 overclocked with standard cooler to 3200 mz - it gets to 50C max and gives good performance. I am seriously tempted to get the Q6600 as an upgrade. I am not looking for the earth - but a little upgrade until a new computer in 18 months or so.
But - will the performance boost be worth the extra cash? I only fly FSX and on medium setting get about okay: - it averages 18 fps.
But - will the performance boost be worth the extra cash? I only fly FSX and on medium setting get about okay: - it averages 18 fps.