I personally am in pretty much the same situation. I have an e6400 and are planning to upgrade after the July 22 Intel price drops. I am deliberating between an e6850 and a Q6600. I originally thought that the Q6600 would allow me to do more, still be faster than my current processor, and have better support for multi-threaded apps. I also assumed that the e6850 would be better for gaming (since I have an 8800 and several DX10 games). Crysis is going to be multi-threaded so a Q6600 would be better for that. But, after reading the Tom's Hardware CPU comparisons I was slightly turned off of the e6850 (especially considering the future possibilities for a quad). Reference these: http://www.tomshardware.com/2007/07/16/cpu_charts_2007/page34.html#3dmark_06. These are the 3dmark06 and PCmark scores. I orignally figured that the e6850 would take the Q6600 in 3dmark and the reverse for PCmark. But actually, 3dmark shows a somewhat considerable advantage to the quad, ESPECIALLY in the CPU test. In the CPU test (which is to be expected) the quads have no match. CPU test under PCmark also shows a win to the quad, but the in the memory test the e6850 beat all. Thus, I am now highly considering the quad core, especially considering that I run Vista (for which multiple cores is useful) and that you will begin to see more and more apps that can take advantage of four cores. The Q6600 and e6850 are going be the exact same price after the drop: an amazing $266. This is why I wouldn't consider any other processors. The e6850 is the best dual core by far and the Q6600 is half the price of the Q6700 while, clearly, still offering amazing performance. For $266, that is hard to beat. Now, I am not sure about your motherboard, but my Asus P5B-Deluxe has a bios update that allows me to run the e6850 in "FSB1333 mode." Your motherboard may have such an update as well, in which case, purchasing a new motherboard now would be essentially pointless. You can always do so later. Here are the new Intel proc prices after the July 22 drop (which is gonna stick it to AMD):
Quad Cores -
QX6850 (1333 FSB): $999
QX6800 (1066): $999
Q6700 (1066): $530
Q6600 (1066): $266
Dual Core (4mb L2 Cache)-
e6850 (1333): $266
e6750 (1333): $183
e6550 (1333): $163
e6540 (1333): $163
Dual Core (2mb L2 Cache)-
e4500 (800): $133
e4400 (800): $113
Dual Core (1mb L2 Cache)-
e2180 (800): not sure
e2160 (800): $84
You can obviously buy the Q6600 or 6700 without any change of motherboard or updating. Personally, I suggest the Q6600 or e6850. I am not sure about price drops of the current e6600's or e6700's but I am sure they are to drop as well. But, with the price of either that extremely fast dual core or the quad, I would go with one them. Can't beat it for that price. Also, there will be some August 26 price drops, but you can be sure that they won't halve the prices again! Great time to buy a new processor, even with a new line leering around the Christmas corner. Hope this helped.