As you work more and more with computers/documents, you tend to pick up little shortcuts here and there on how to do some common, everyday tasks more quickly.   
Microsoft has a great listing here:  http://windows.microsoft.com/en-us/windows-vista/Keyboard-shortcuts

Some of my favorites are:

• CTRL+C -- Copy the selected item
• CTRL+X -- Cut the selected item
• CTRL+V -- Paste the selected item
• CTRL+Z -- Undo an action
• CTRL+Y -- Redo an action
• Windows logo key +E -- Open Windows Explorer
• Windows logo key +F -- Search computer for files
• Windows logo key +P -- Print
• ALT+TAB -- Switch between open items
• F2 -- Rename the selected item

Try one or two out today.  Once you get familiar with a shortcut, you’ll wonder how you ever managed without it!

Wikipedia’s Table of Shortcuts (includes MAC shortcuts):  http://en.wikipedia.org/wiki/Table_of_keyboard_shortcuts