in almost every benchmark i've seen, 45nm = runs cooler, and the quads have a huge improvement in basic math calculations...like the ones used in most audio applications for rendering sound, reverb, delay, etc.
the q6600 is a hot processor naturally - it runs a lot more than other quads because of it's (relatively) low l2 cache. it's worth spending a bit more on getting a q9450 or something is good. of course, based on what you're running right now, an e8400 would be well worth the cost, as well, since there aren't any audio programs out there that can utilize all four cores anyways. it's easy to overclock them on stock cooling to something like 3.3 or 3.4 without even trying...i've got a step lower, the e6850, and it's sitting at 3.3 with a shitty intel stock cooler, and it runs cooler than my e4500 did way back when.