If you simply want to read data from an XML file into your script for use, setting up an event-based parser might seem like overkill. Luckily, PHP provides a much simpler alternative in the form of SimpleXML, an extension designed to make XML use as straightforward as possible, and is actually core to PHP 5 because it does all of what the vast majority of users need. Many have referred to SimpleXML as "XML for Dummies", but don't let that put you off - all types of people use SimpleXML, regardless of their experience.
SimpleXML works by reading in all the XML file at once and converting it into a PHP object containing all the elements of that XML file chained together in the same way. Once the file has been loaded, you can simply pull data out by traversing the object tree.