i am currently running an e6600 at 3.2 ghz, and am thinking of doing a cheap upgrade to an e6850 and overclocking to 3.8 ghz.will i see much of a difference?

What game are you running? That's about 16% increase in CPU frequency which may or may not help depending on where your game is limited. For FSX it will probably help a little since FSX is CPU bound, but for FS9 it probably won't make a difference and a video card upgrade may help more.