First off, Hibernate and Standby aren't Power Schemes. They're
power states into which the computer can be placed. They can be
settings within a Power Scheme. It sounds like they're missing
from Power Options on your computer.
When you open Power Options, is this what you see?
http://www.guidebookgallery.org/pics/gui/settings/power/winxppro-1-1.png
If you're system supports Standby and Hibernate, you should see
this.
http://img.microsoft.com/library/media/1033/technet/images/prodtechnol/winxppro/evaluate/mblxp01.gif
Let's start with hibernation. In Power Options, click on the
Hibernate tab and make sure there's a check mark in the box
next to "Enable Hibernation". If you see an APM tab, click on
it and put a check mark in the box next to "Enable Advanced
Power Management support". Now click on the Power Schemes tab.
You should see an entry at the bottom of the Settings box for
"System hibernates".
As for System standby, make sure you have the latest drivers
for your display adapter installed. Go to your computer
manufacturer's support web site to download the latest drivers.
If you have a separate video card, check that manufacturer's
web site.
If you run into any problems, post back with information about
your computer and video card. Include make and model #.
Good luck
Nepatsfan