To jQuery or not to jQuery

I’ve been working on a few little web apps in my spare time and I’ve been writing them in the traditional AJAX (php, javascript, xml), but did some reading and found a lot of people using jQuery to code their AJAX.

My question is. Does it make it worth the ease of coding to switch to jQuery although I have to install jQuery on top of my applications? Rather than stick to what is available to me through php & javascript?