I recently volunteered to work on the code my employer offers with its product for integrating with the free software learning management system, Moodle. Moodle is PHP based, a language I’ve only used sparingly, mostly in the form of WordPress hacking. A coworker recommended PHPEclipse as a free tool to make the Moodle hacking more tolerable.
I wish I had seen this comprehensive round-up of PHP tools on Slashdot sooner though. I have a strong bias towards Eclipse born out of laziness–I’ve used Eclipse for Java hacking for years and also recently installed PyDev to ease my Python hacking activities. I’ll probably stay with Eclipse, though I may check out the Eclipse PHP Development Tools (PDT) as I have been impressed by similar bundling efforts around enterprise Java in recent years.
If you are looking for tools, or hadn’t realized how many were on offer, I’d recommend taking a look at the Infoworld article. At a minimum it may support the choice you already made but it is always good to occasionally check to see if you might be missing something better.