This problem has completely shot my entire day. I reformatted my old windows XP comp and tried installing XAMPP only to find that when i try to start Apache xampp claims por
This happens because some other programs running in your system is using the default port 80 used for http service by apache server in xampp/easy php.
Some programs like skype usually use port 80. so find such program and remove it ...
For finding programs listening port 80 refer Port 80 listening programs