What do you expect to accomplish with a memory upgrade? If you are running at stock clocks, you will see no increase in speed. If you can overclock, you can run your CPU at 3.3 GHz and still stay within your memory's capability.
My opinion, a memory upgrade for speed is not worth it.
BTW I am running Windows 7 Ultimate 64-bit edition. An Increase from 4.0GB to 8.0GB will have absolutely no effect at all? and also I can't over clock my CPU more that 2.9GHz it has locked multiplyers "Q6700" I dont have the Intel Extreme Edition QX6700. I don't know why I cant overclock more. At 2.9GHz my CPU Temp goes to only 35 'C and usually and stock speed 2.6GHz its 29 'C to 30 'C. Any advice on this matter as well I would really appreciate.