If you're looking for a basic screenshot tool, ScreenCapture might be for you.
ScreenCapture doesn't require installation, meaning you can keep and run it from a USB pen drive. It's also incredibly small and lightweight. The interface has two main buttons, Capture Area or Capture Screen. It's very simple, and your capture is saved to the clipboard. There's a button to open Paint, so you can paste in the image, save it or edit.
There are no options in ScreenCapture, and it doesn't minimize to the system tray. It's completely stripped down, with no editing features at all. Paint is probably not the application of choice for editing screenshots either!
As a totally basic way to take screenshots, ScreenCapture is absolutely fine, but there are much more complete similar programs that give you a lot more flexibility.