Question : How to enable hibernate acpi in xp 64 bit on dell optiplex 760

dell optiplex 760 desktop, installed oem windows xp with sp2 64-bit
installed all windows updates and all hardware drivers i could find.
the hibernate tab is missing in power options, however computer mgmt reports an acpi enabled processor.
how can i enable hibernation and make acpi active ?

installed drivers:
- Intel Graphics for XP 64 r14.41.0.64.5160 - 6.14.10.5160
  Intel Q43/Q45/G43/G45 (Eaglelake) Graphics Controller
- infinst 9.1.1.1025
- intel 82567LM-3 nic A02_R252705 r11.5.4.0
- R228747 audio 5.10.02.7255, A10
- viewsonic Standard_Monitor_Driver_Unsigned_Win_x64 1.5.2.56
- Intel_AMT-HECI_A00_R197546 "pci simple comm. ctrl"
  Intel(R) Management Engine Interface 5.0.1.1055
- Intel_AMT-SOL--LMS_A00_R197547 "pci serial port"
  Intel(R) Active Management Technology 5.5.0.1057

Answer : How to enable hibernate acpi in xp 64 bit on dell optiplex 760

Hibernation is not supported in xp64 - see http://www.microsoft.com/whdc/system/platform/server/PAE/pae_os.mspx