most 12 useful Keyboard Shortcuts in windows 7 (and xp)
Alt + Enter: Display properties for the selected item.
Alt + F4: Close the active item or exit the active program.
Alt + Tab: Shift between open programs.
Windows + Tab: Shift between open programs.
Ctrl + Z: Undo last action.
Ctrl + Shift + arrow key: Select a block of text. (or Ctrl + Shift: select text)
Ctrl + Shift + N: Create a new folder anywhere on your computer where folders can be created.
Shift + Del: Delete an item without sending it to the Recycle Bin.
Ctrl + Shift + Esc: Open Task Manager.
F1: Display help.
F2: Rename the selected item.
F5: Refresh the active window. (or refresh a site web)