FastStone Capture is your friend. FastStone Capture 5.3 is a free (for private use) screen capture utility that is fast, portable, and easy to use. It is probably available many places, but I grabbed mine at Portable Freeware http://www.portablefreeware.com.
It has a nifty floating toolbar, and a good configuration panel via the taskbar. Also, it has its own editor, allowing easy crops and edits.