index.php forwards requests to your Xampp's folder when yopu type "http://localhost". I recommend you leave it as such, however if you want to see your another website instead of the localhost when you enter you local IP address (192.168.1.xxx), then make changes in your "httpd-vhosts". In "httpd-vhosts" the access goes to the first <VirtualHost *:80> in this group.
Make sure your first <VirtualHost *:80> is not localhost but the one you want to show, like:
<VirtualHost *:80>
ServerName zingout.com
DocumentRoot c:\xampp\htdocs\www\zingout
ServerAlias
www.zingout.com
ServerAdmin
services@zingout.com
ErrorLog c:\xampp\apache\logs\zingout-error.log
CustomLog c:\xampp\apache\logs\zingout-access.log common
</VirtualHost>
<VirtualHost *:80>
ServerName localhost
DocumentRoot c:\xampp\htdocs
</VirtualHost>