Which of these processors is better for gaming would be largely based on the game. More games today are adding support for multi-threading but most of them are still top out at 3 or less threads. Even if the software does take advantage of more threads it may not get much of a performance bump from multi-threading. With a 1GHz clock speed difference, I would think that most of the time you would find that the Intel® Core™ 2 Duo E8600 is the better processor most of the time.
Intel Enthusiast Team