You can take a screen shot of your pc in 2 different ways in Windows Vista or Windows 7.
First, the classic one (works on Windows XP to).
1. Press “Prt Scr” key. Windows will copy to the clipboard a capture of the entire screen.
2. Open Paint application (Start -> All Programs -> Accessories) than hold ctrl key and press v key to paste the capture image.
3. Save it.
If you want to create capture of a single window you should hold alt key and press “Prt Scn” key at step 1 above. This will create a clipboard copy with the capture of your active window (not to the entire screen).
Second, the snipping tool.
You can use Snipping Tool to capture a screen shot of the entire screen or snip objects on your screen and save them as pictures. To do that
1. Open Snipping Tool by clicking the Start -> All Programs -> Accessories, and then click on Snipping Tool.
2. Click the arrow next to the New button to select a snip type from the menu then use your mouse or tablet pen to capture a snip.
3. Click the Save Snip button.