Also on a triple core, try an affinity mask setting of 6. That should make it run smoother (though not faster).
That will make the operating system and background processes run on core 0 leaving cores 1 and 2 to run FSX smoothly without interuption for the stuff that is now being run by core 0.
Insofar as Bjoote's service and tweaks are concerned, I found that most of them work better on high end systems with high video memory. Wouldn't hurt to try them though.
Q9550 @ 3.78 GHz with Gainward GTX570 1.25 Gig DRAM
4 Gig DDR2 RAM - Windows 7 64 Bit
Resolution 1680 X 1050 X32