Hi,
Default Pictures are stored here:
Windows Explorer\Documents and Settings\All Users\Application
Data\Microsoft\User Account Pictures\Default Pictures
HOW TO: Add or Change a User's Picture in Windows XP
http://support.microsoft.com/default.aspx?scid=kb;EN-US;q292434
How to Add a Specific Picture
Find a picture you are interested in using and use Save As to download
and/or move the picture in question to your My Pictures Folder. Then go to
User Account/Change my picture/Browse for more pictures/My Pictures
Folder/Choose the picture you want to use, then click Open.
Summary of an image is 48x48/71 dpi, depth 24.
Note: If you have disabled Picture and Fax Viewer by using
regsvr32 /u shimgvw.dll, you will not be able to change the picture.
To restore, go to Start/Run and type in: regsvr32 shimgvw.dll