Is a 4-7C difference between core 0 and core 2 okay on a Q6600? I've already reseated once and I applied TIM correctly. If it's too much, I can reapply, but I'm just not sure.
3-4 is normal... 5-7 is probably fine, 7-11 and like others have said, you'll probably wanna reseat. Older Q6600's (maybe G0's I dunno) have pretty shitty IHS compared to the 45 nm stuff (well, I can't say that since I've only seen one 45 nm quad and it was a xeon which I just bought a few weeks ago).
Not all Intel chips need to be lapped these days. My X3360 came very flat which is in stark contrast to my Q6600 a year ago. I haven't lapped the X3360 or the new TRUE and I have great temps (low and even).
Here's a low-res comparison of the two; note how much flatter the X3360 is on the corners:
If you wanna see just how unflat the Q6600 was, have a look before/during/after pics of lapping it in this thread. For the TRUE, see this one
Anyway, as I said, I didn't do the X3360 or the new TRUE. Here are the temps:
Idle
Load (p95 for 10 min with room temp being 72 °F (22 °C).
I had to lap my Q6600 and the base of my TRUE to get not only lower temps, but more consistent temps. If they really bother you, I'd recommend that you lap them both as I did.