I had to load Quicktime on my PC for one reason or another in the past few months. It's not generally a package I load, but, apparently I needed it for some reason. I of course did the extra legwork to find the Quicktime installer that didn't include iTunes, as I also don't have any use for iTunes. In the past few weeks this really annoying dialog started popping up periodically hawking not only some new QuickTime build, but also iTunes.
I have been clicking Quit for weeks now and it's been getting old. I hadn't really invested the time to figure out where this annoying application was launching itself from, but, tonight I stumbled upon the answer by accident. Check your scheduled tasks - apparently Apple took the liberty of installing a job that runs this update application of theirs. I deleted the job - hopefully it doesn't come back and hopefully I don't see this dialog anymore:
