You know that when you have a lot of files and windows application that are open now and you wanna come back to your computer and continue your job, only with hibernation feature you can do this.

 For enabling this feature in your Windows XP, you should login to your computer with administration rights, click on start button>Control Panel, click on performance and maintenance the click on Power Options. A "Power Options Properties" dialog box will appear, select Hibernate tab and then select the "Enable hibernation" check box to enable the hibernate feature. Now click on Apply button to implement the changes then click on Ok button to end the configuration process.  It's done, now if you click on "Turn off Computer" you will see the hibernate button.