" Desktop/My Documents/My Pictures" isn't a real path. It's similar to a short-cut to a folder that changes with each user.
To find what the real path is you can open "My Pictures" in explorer and right click on the address bar. Then choose. "Edit address". The address bar will then show you the absolute path which will be something like C:\Documents and Settings\user name\My Pictures (XP) or C:\users\user name\My Pictures (Win7/Vista).