When it comes to create screenshots, I often use MWSnap, a freeware written by Mirek Wojtowicz. This tool offers all the core functionalities one may expect from a screenshot application. MWSnap was recommended to me by Michael Olivero.
The tool allows snapping variable rectangle areas as well as entire windows and menus. The snapped images can then be saved as jpeg or png. The ability to edit the snapshot by adding cursors is handy to document user interaction. Finally, the auto-saving functionality with auto-generated file names will increase productivity for high-volume scenarios.
MWSnap has been released before the advent of Vista. Under Vista, most of the functionalities of MWSnap work, but some glitches are expected when snapping windows and menus.