Max Horvath recently posted a how-to on getting the XDebug debugging support up and working in the Zend Studio for Eclipse software.
Zend Studio for Eclipse is a commercial edition of Eclipse plus the PDT plugin and various other additions. Unfortunately Zend decided to disable the Xdebug support of the Eclipse PDT plugin. Nonetheless if you'd like to use Xdebug for debugging your PHP scripts, follow these simple steps to restore the Xdebug functionality of Eclipse.
Its a simple six-step process (not including getting Zend Studio installed) to have the powerful debugging tool ready at your fingertips. You can find more information about setting up the tool here.