These keyboard shortcuts will help you perform faster and better and every Windows user should know most of these as these are the essential ones !!
Windows System Key Combinations

F1: Help
CTRL+ESC: Open Start menu
ALT+TAB: Switch between open programs
ALT+F4: Quit program
SHIFT+DELETE: Delete item permanently

Windows Program Key Combinations

CTRL+C: Copy
CTRL+X: Cut
CTRL+V: Paste
CTRL+Z: Undo
CTRL+B: Bold
CTRL+U: Underline
CTRL+I: Italic

Here is a list of 97 commands that you can type in at command prompt or in RUN ( Start->Run) to launch various utilities
Accessibility Controls - access.cpl
Add Hardware Wizard - hdwwiz.cpl
Add/Remove Programs - appwiz.cpl
Administrative Tools - control admintools
Automatic Updates - wuaucpl.cpl
Bluetooth Transfer Wizard - fsquirt
Calculator - calc
Certificate Manager - certmgr.msc
Character Map - charmap
Check Disk Utility [...]

Need your Windows Vista or Xp to shut down faster and quicker , Try this registry trick to shutdown your Vista,Xp as fast as possible .
Caution: If you are a newbie ,You can read http://support.microsoft.com/kb/322756 for more help on how to take a registry backup.
If you are a Windows XP user, then read this else [...]

Here are a Few Easter Eggs and Windows hidden tricks for you guys, added them to make one big collection .
System Protected Folders
Ever notice that in the Program Files folder there are two folders that you can’t delete? Xerox and Microsoft Frontpage?
Reserved files and folders
You can’t create a folder called CON, AUX, COM1, COM2, COM3, [...]