I am currently using a e4500 stock. Unknown to my father, some other relatives leaked information on what he has gotten me for Christmas. Which happens to be a q6700. So my question is this; Will I see a "noticable" improvement in performance? I mostly play games, recenetly being Dragon Age and Call of Duty, and Adobe Photoshop CS4 for class work.
I did a similar upgrade and was extremely happy. I had an E4500 and upgraded to a Q6600. The Q6600 overclocks better than the Q6700 but you'll definitely see significant bump in performance.
IMHO the Q6600 (and to a lesser extent the Q6700) is one of the best performing CPUs for the buck that Intel has ever released.
The E8400 is probably a better choice for gaming but for me the Q6600 was the best choice as I built a server to host multiple virtual machines.