Note: This article assumes that you have a working Apache/PHP environment running with the latest major version of Netbeans (current 7) installed.
Xdebug is a brilliant PHP extension that provides both debugging and profiling tools. From a basic install it will vastly improve the quality of the error messages but it can also be made to interactively debug scripts using a number of different IDE's. It can also be used as a code profiling tool, but I won't be going into that in this post as that is a little beyond the scope of what I will be talking about.
If you are using XAMMP to host your Apache/PHP environment then you can skip the following step. Xdebug is actually bundled with XAMMP so you just need to enable it by going into your php.ini file and uncommenting the options you need.