As far as I've heard the qx6700 can do 3.2GHz on stock cooling, which is being said to be quite decent, although noisy. With a Big Typhoon and a well ventilated case you should be fine @3.2GHz.
Since the money don't seem to be an issue I'd advice you to give another 90$ on a Pentium D 805 and OC that one for the starters, afterwards you can sell it. OCing ain't so dificult, but screw-ups are possible. You would prefer to screw up a 90$ CPU better than a 1300$ one, won't you? Consider it as a warm-up
That Pentium D 805 sounds like a good idea,i will look at getting one of those first.
I was thinking about going water cooling but i have a feeling that this clloing method would be a lot of maintenance.