It depends how much you value that extra speed. It sounds like the application you could benefit most from is video encoding. Will it matter to you if your job gets finished a little bit faster? If you’re doing it a lot, then it probably is worth it. This is all of course if you are not using Quick Sync to perform the transcode.
Your gaming may also benefit a bit depending on the game and whether it is CPU bound.
It sounds like you are pretty satisfied with the Q6600 performance so in that case, save the $100.
