"0" Blank File, and Clock AVI File

For Windows XP, If you look in your "My Computer\C:\WINDOWS\" In this folder, after all other folders, you find a text file named "0". If you open it, nothing will be in there, hence the filename "0".
Another thing would be a file called "Clock". It's an AVI file. It can open it in Windows Media Player. It's a very simple and plain animation.