Stock cooler Phenom II x4 noise

Having just read the article "Is It Worth Upgrading Your Stock CPU Cooler?" (which was more or less Intel-bases), I was wondering:

I'm planning to build a PC in the near future, based around a Phenom II x4 945 (or 955). OC'ing is not planned, but might happen in the future, although I doubt it. One of the requirements is that it has to be fairly quiet. Not exactly noiseless, but quiet nevertheless. For a graphics card I'm considering a 4770 (or a 4850). However, will the stock-cooler on the Phenom be quiet enough (considering that maybe the case-fan has to work harder), or is it worth spending another $30-40 of cash for, let's say, a OCZ Vendetta2? My total budget shouldn't exceed $800 (incl. OS).

I have a Scythe Ninja-mini on my 720BE. I selected it based on the charts at www.frostytech.com. Even though it is 80mm, it is essentially inaudible, even though it runs full-speed all the time (fan is not PWM).