There’s an option in XP that allows set a period of time, after which your monitor will be turned off. (which is more like Standby given that a shake of will awaken it).
Here is a way about creating a shortcut that will allow you to do the same?
OK you can have two ways to do this
1.Use this widget for Yahoo! Widgets Engine OR Konfubulator
2.Another way is to download a standalone program that is built for this
Check out the page http://www.nirsoft.net/utils/nircmd.html
1. Download the ZIP file (link is of that page).
2. Extract it to a temp folder.
3. Run nircmd.exe file.
4. Click “Copy to Windows directory”, click Yes.
5. Now, right-click desktop (or inside any folder like Start Menu, Programs, Quick Launch) and select New>Shortcut.
6. Enter “nircmd monitor off” or “nircmd monitor low” (no quotes please) (I don’t know them. Experiment.).
7. Click Next, and enter “Turn Off Screen” or anything you like as shortcut name. (no quotes). Click Finish.
8. Right-click the shortcut you created, and click “Properties”. Click “Change Icon”
9. If a message “The file %windir%\nircmd.exe contains no icons.” (or similar) appears, click OK.
10. Choose a nice icon (In WinXP, I use the “blue power icon” of shell32.dll file).
11. Click OK. Click OK again.
12. Try out the new shortcut to get a feel of it!