|If you have installed XP from scratch, you must install the main chipset drivers for your mboard in order for Windows to have the proper info about how your mboard supports Standby, Hibernate, and other ACPI features. |
Control Panel - Power Options
If Standby is set to Never come on, it won't appear in your Turn off menu.
You don't need to use Standby mode in order to have your display or hard drives shut off after xx amount of time of user inactivity - those can be set in Control Panel - Power Options .
If you have an old mboard - older than about 2001 - the mboard's support of ACPI modes may not be compatible with XP's support of them - if Windows finds Standby or Hibernate doesn''t work properly, it may prevent you from using Standby or Hibernate modes, or tell you there are problems with Standby and ask you if you want to disable it - if you answer Yes, then Standby mode is no longer available.