At first I thought your CPU temp was a bit higher than it should be, as my e8400 @3.6 only reaches 52C while stress testing with Prime95. However, after downloading and running IntelBurnTest, I see that my chip hits 59C with that stress test. So there is very little difference between the two, and that difference could be the fact that your CPU's core voltage is higher than mine.
I noticed the same thing as moody89 as well. Your GPU temp is much worse than the CPU.
Yeah, if it was my chip I don't think I would push it any further with those temps. I don't know how much higher it can safely go, even though the TJ Max is 100C. I feel your pain about not getting to 4GHz. My motherboard (P35-Ds3l) is extremely unstable at anything over 400MHz bus speed, so I'm stuck at 3.6 as well..