I use Gadwin's PrintScreen. It's freeware, and can be keybound. It occasionly screws up when trying to screengrab a old game (Fallout 2 and older). Apart from that, the only other problem it has if you're trying to screengrab a video being played with VLC. But that has it's own in built grabber. I've been using it for five years now and it's literally the only program I've not looked for a replacement for.
It works fine with 7, but I don't know about a 64 version.