Kelly Forrister has a great tip on the Simply GTD Blogs:
“Feel like you’ve gone numb to the Reminder windows that pop up on your Calendar? (Hint: answer yes if you find yourself clicking snooze or dismiss most of the time when you see that window.) Don’t feel bad. Most programs are built to help you to go numb to those Reminder because they set them on everything that is timed.
I’m not saying don’t use reminders–just use them sparingly so that when they go off, they actually mean something.“
She describes in detail how to disable reminders by default in Outlook and other tools. Excellent advice if you haven’t already done it.