Gadwin Printscreen works really well (http://www.gadwin.com/download/). Freeware and plenty of options. You could also download a cracked version of Fraps (so you can take videos too).
I haven't looked at Gadwin, but my organization uses SnagIt. SnagIt is real nice in that when you hit Prt Scrn, it "freezes" everything on your screen and allows you to select what you want to copy by dragging a box around it.
Then it will open into its program where you can modify it, send it via email or save it.
