How can I prevent applications from running on startup? Possible Duplicate:
  How can I stop applications and services from running?  




I've installed some applications that I mostly like, except for the fact that they all decided they were too important not to auto-start.  None of them give me any option within the application to disable the auto-start "feature."

Can I stop these applications from auto-starting?  And if so, how?

Note: My phone is not rooted, so I'm especially interested in solutions that do not require a rooted device, but all answers are welcome, even if they require rooting the device, since I may do this eventually.

Also note: I'd prefer not to fiddle around with clumsy auto-kill features in task-killer programs, as I've found them to be incredibly unreliable on my phone (Motorola Milestone/Droid).
Please, please, please, please put down the task killer.

It isn't needed.  The operating system knows how to handle and end applications just fine.  Otherwise you are going to waste performance/battery because when you kill a task it is going to re-spawn back up.  And if you  killed a task that was writing to disk (or a database), then you could potentially create corruption.

The only time you ever, ever, ever should kill a task is if it is obviously running wild or hung up (and usually when this happens you get the Force Close screen.  If not, go to Settings --> Applications --> find your app and kill the task there).