I use this to take screenshots, you might find it comes in handy. You can take a snap of the current desktop or a section of the desktop.

MW Snap

Not to be rude, but to copy a screenshot of the screen, you could just press the "prt scr/sysrq" button on your keyboard (a.k.a. the "print screen" button) next to scroll lock, two up from the delete button on most keyboards. After that you can use the paste button on most any graphics program (like Paint or Photoshop) to edit and/or save it.

Although I can see how this program would be helpful for selected windows, converting, and other things of that nature, It's not necessary for quick snapshots.

Hope this helps