Arctic Cooling Freezer 7 Pro. Best read reviews to see if that cooler fits it, some motherboards like the Asus P5Q Deluxe won't fit the ACF7P without some modifications. It costs only $19.99 from Newegg.
No, that cooler absolutetly will not bend your mobo.
The problem is that the push pin design that mimics the stock cooler retention system is absolute crap. It is a pain to install and often works itself loose.
DO NOT USE THE PUSH PIN RETENTION DESIGN.
That cooler fits well in the 300, I have use it in one, and it works like a champ.
If you decide to use it, then be sure to cover the whole CPU IHS with a very thin film of TIM, because the heat pipes don't allow for proper spreading through contact. An alternative, as per Lupiron, is to run a bead down each exposed heat pipe on the base.
Thanks everyone! I am ordering it now. I decided to change my case to the Coolermaster as suggested and get the 750W power supply, both from Buy.com. I'm going to hold out on the cooler for now but I'll probably pick it up next month or something.