Make this change to Skype configuration to allow Skype and Xampp to work together (from http://www.apachefriends.org/en/faq-xampp-windows.html#startpage ):
If Apache doesn’t start while Skype is running, change the settings on Skype to not use port 80. Skype’s Tools, Options, Connection tab, uncheck “Use port 80 and 443 as alternatives for incoming connections”.
