stopthekilling77 is correct. Not many programs are optimized for quad core cpus. (only a few major dev companies make an effort in making their software quadcore optimized/compatible , like photoshop) If you are a gamer then you may want to go for a Core 2 Duo because the differences are minimal or ...
my 8800GTX goes to the high 70s and on a really hot summer day 80-81 when gaming.
It all depends on the air circulation in your case too. A well aired case can take as much as 5° of your temps.
I got my E6700 running at 3.2ghz. I know its just a mild overclock but everything works, its stable and cool and most important fast for me
Maybe when I'll actually need some faster speed i'll oc it some more. But for now its dead fast