I read that apache web server can't open socket on port 80.
This could be related to your firewall or to skype...
Try to open port 80 for localhost on your firewall and launch xampp before opening skype, I remember that for some reason, skype on win uses and blocks port 80...
Maybe you will need to configure your apache virtualhost for your moodle instance, please refer to the apache documentation for more information about it.
Hope this can help.