CPU benchmark tests

I am currently considering upgrading the CPU on one of my pCs with a socket 775 motherboard to a QUAD core CPU in an attempt to get higher frames per second using Flight Simulator X.
I have checked www.cpubenchmark.net for the benchmark tests for the existing CPU (E6850 3.0 Ghz 4Mb L2 cache) and also a possible quad core cup (Q8300 2.5Ghz 4Mb L2 cache) and note the following 'passmark' values -
E6850 1926
Q8300 3550
Does this mean that the Q8300 generally is at least 50% faster than the E6850?

One thing which I could not understand was that the figure for a E7500 2.93Ghz 3Mb L2 cache (the CPU in my other PC) was 2012 which is slightly better than the E6850 yet it is slightly slower and has a smaller L2 cache - this doesn't make sense.

Can anyone give me 'the good oil'?

 

Already done that with a small improvement but I have been told that FSX is CPU intensive.