Tip 6 : Configure the Windows XP logon screen saver

5. Configure the Windows XP logon screen
saver
As always, remember that editing the registry is
risky, so be sure to back up your computer before
undertaking any registry changes.
If you ever work in a computer lab or an Internet
café where systems regularly sit idle waiting for
someone to log on, you know that Windows XP will

display the Logon dialog box or the Welcome screen
for 10 minutes before running the default logon
screensaver-the Windows XP logo floating on a black
background. You can change the default logon
screensaver to something different, such as the
OpenGL 3D Pipes screensaver, and you can shorten
the amount of time Windows XP waits before
activating it. Here's how to do both:
1. Launch the Registry Editor (Regedit.exe).
2. Go to HK_USERS\.DEFAULT\Control
Panel\Desktop.
3. Locate and double-click the SCRNSAVE.EXE
string value.
4. In the Edit String dialog box, type the name of the
screensaver you want in the Value Data text box and
click OK.
5. Locate and double-click the ScreenSaveTimeOut
string value and change the value from 600 seconds
to another number, such as 120 for two minutes.
6. Close the Registry Editor and restartWindows XP.
After the system restarts and you see the Logon or
Welcome screen, leave the system untouched for two
minutes to see your new screensaver in Action.

Courtesy : @internet.info