Hey, don't wait until July 22nd! You can buy the Q6600 off of Newegg for only $480!
As for being compared to the E6600, that only costs $222 on newegg! So if you're willing to pay more then double for Core 2 Quad, go for it. If you're not, just stick with the E6600, as that processor is still amazing. My dad put one in the workstation that I built with him and it's amazingly fast, and handles multitasking and gaming perfectly. I'm sure the quad core can do it better, but it really depends what your going to be using it for.
For example, if you are going to be running one application at a time, that only supports 1 to 2 threads, why put out the extra 260 dollars? Now, if you're going to be doing lots of multitasking with tons of apps, or gaming with the newest titles that support up to 4 threads, and if you have the money, go for it!
Just make sure your motherboard officially supports quad cores.
