Turn on Hibernation in Windows XP and Vista

To enable Hibernate in Windows XP, right mouse click on empty place of Desktop and click properties, it will bring up Display Properties. Click Screen Saver tab and click Power

You may set Screen Saver and other settings related to Screensaver.
Select Hibernate tab, check Enable hibernation and click Apply to save changes.

Done :) you have successfully enable Hibernation. You may Hibernate your computer using one of the following procedures.

• Open Windows Task Manager, (Ctrl Alt Del or right click on Task bar and select Task Manager) select Hibernate from Shut Down menu.
• Click Log Off from Start Menu » press and hold shift button, Stand by button will change to Hibernate » click Hibernate.
• Assign Hibernate command to your casing power on button, to do so, take the following steps.    
        
  1. Bring up Display Properties » Screen Saver » Power » Advanced.
        
  2. Select Hibernate from When i press the power button on my computer » Apply to save changes.