Going from the QX6700 to the QX6850 makes Adobe Photoshop CS2 work about 8% faster, while the QX6850 was 15% faster than the Q6600. The QX6850 completed the benched task 19 seconds faster than the Q6600, which is impressive but does it justify the significant difference in price between the two?
In Pinnacle Studio Plus the QX6850 is 10% faster than the QX6700 and 18% faster than the Q6600. Again these are reasonable performance gains but in the overall scheme of things this will not save you a great deal of time.
Once again similar performance margins between the QX6850 and QX6700 exist, with the newer and more expensive being 10% faster. This time the Q6600 is 20% slower than the QX6850 (or approx. 90 seconds faster).
All three quad-core processors are very effective when used in conjunction with 3D Studio Max, though the Q6600 is not really much slower than the QX6700 or even the new QX6850.