If you want to take screenshots in Windows 7 beta, this OS comes with it own little program called Snipping Tool, which can be found in the Start Menu/All Programs/Accessories.
You can take a screenshot of the entire screen, a window or just a selection of the screen, that you select. Below you can see a crop I did on a small portion of my wallpaper.
Great! This is EXACTLY what I was hoping/looking for.