List of hidden programs in windows XP is given below
Dr. Watson
This is an inbuilt windows repairing system. To open this wizard go to Start-> Run and type "drwtsn32".
Private Character Editor
Used for editing fonts. By using this we can create our own customized system fonts. To open this go to Start->Run and type "educedit".
Media Player 5.1
This is a good player for playing songs and videos. This is inbuilt in Windows XP. To open this facility go to Start->Run and type "mplay32".
IExpress 2.0
Used to create customized installers. That is we can create our own installers using this facility. To open this go to Start-> Run and type "iexpress"