As I said in my first post I'm getting back into simming after a break, and I don't want to get into a situation like I was in before where I spend more time tweaking my system than actually flying. However, as it is right now with my setup frame rates are borderline, so I guess I'm going to have to do some tweaking, like it or not. In the mean time I will check out those aircraft you suggested. The Eaglesoft aircraft look tempting; the RealAir aircraft are geared more towards VFR.
EDIT: Well I turned my computer off for an hour to let it cool down then I pulled the CPU all the way out. No problem at all, so I decided to go ahead and get that E6850.
I maxed out all the graphics sliders (the only custom setting I changed was the screen resolution, which I set 1680x1050x32 to match my monitor) and sitting at LAX, runway 25R, Fair Weather, Day, using the FSX G1000 172, I'm getting roughly 14.5 FPS in the virtual cockpit (when it first loads--it drops to about 11.5 after a minute or so). That will be my bench mark for the new processor.