[davidw]

Ok, here's a 30 second random thought for those wanting users to control the option. Don't shoot me if it doesn't work, because I've not tested it.
Go into your admincp and create a new user profile field. 2 choices yes no.
Put in the header an if statement - like <if condition $userinfo[field99] == 1 (or yes or whatever) or whatever the syntax is (can't think at the moment). then the script - that way if it meets the criteria then voila!
Ok, off to bed :P