Windows Key+E
The best part about shortcut keys is letting your keyboard do half the work. This is a perfect example: This shortcut allows you to open Windows Explorer with one quick keystroke.
Windows Key+M
This is the shortcut to keep in mind when you are at work doing anything but working—it allows you to minimize all of your open windows, leaving just the desktop left exposed. To restore the windows, hit Windows key+Shift+M. Another quick way to do this is Windows key+D, which shows your desktop; to restore, just repeat the same keystroke. This is a handy shortcut to have around the next time your boss is wandering through the office.
Alt+Tab
This allows you to easily scroll through all the windows you have open. If you're working in Word and referring to something in Explorer, for example, you can toggle back and forth between the two programs. You can also use this to switch between windows in the same program, making multitasking a breeze. Very similar is Windows key+Tab: In XP, it lets you scroll the items on the taskbar, and in Vista, it starts Flip 3D for a fun graphical spin on the same idea.
Alt+F4
This shortcut is a quick way to close a window in any program. Alt+Spacebar+C (which requires less stretching, but more keys) and Ctrl+W do the same thing. Any of the ways will allow you to close a window without using your mouse to hit the X in the upper-right corner.
Ctrl+Arrow Keys
In Microsoft Word, the left and right arrows allow you to move the cursor to the beginning of the previous word or the next word; the up and down arrows will do the same with paragraphs. This is very helpful when editing a document or scanning for any reason.
Shift+Delete
If you want to delete a file—and you don't want to deal with it later in the Recycle Bin—this is the way to go. Just be absolutely sure that this is a file you won't want back!
Hold Shift While Inserting a CD
Have you ever wanted to insert a CD and not use it right away? This shortcut allows you to bypass Autorun when inserting a CD so you can control exactly when you will use a CD you've inserted.
Ctrl+Drag
There are many ways to copy a file, but this just might be the easiest. All you have to do is click on the file, hold, and drag it into its desired location. This works the same as another handy shortcut, Ctrl+C.
Windows Key+U+U
Quickly shut down Windows by hitting the Windows key (don't hold it down), hitting U to reach the shutdown menu, and then hitting U again to shut down.
Windows Key+Pause
Need a quick way to get to the Systems Properties menu without too much thought? Just press these two keys and you'll be brought right to it.
Ctrl+Z, Ctrl+Y
Undo an action by hitting Ctrl+Z; if you change your mind, Ctrl+Y will redo the undo.
Shift + Arrow Keys
Holding shift and pressing one of the arrow keys will highlight text in Word (or a group of Excel cells) without the mouse, selecting in the direction the arrow points.
Ctrl+U, Ctrl+B, Ctrl+I
This one's for Office newbies. It's a snap to underline, bold, and italicize without the mouse if you press Ctrl+U (underlining), Ctrl+B (bolding), or Ctrl+I (italicizing).