If your computer hardware supports hibernation feature of Windows XP (most modern computers support hibernation), then you can enable it in the following way :
- Open Control Panel → Power Options.
- Click on the Hibernate tab.
- Check the Enable hibernation and click OK to enable hibernation.
You can also disable hibernation feature in the same way. Note that you would require hard disk space of the same amount as big as your RAM is. If you have 2GB RAM, then you would need 2GB space on the root partition of your hard disk. This space is used to save the contents of RAM when your computer goes into hibernation. When the computer wakes up from hibernation, Windows copies back the saved contents to RAM.
To hibernate your computer select Start Menu → Shut Down and choose Hibernate as the option as shown :
If you have Welcome screen enabled in User Accounts, you can press Shift key to choose hibernation option when you select Start Menu → Shut Down as shown below :