I'm not sure if you guys have checked this out yet, but ruslany, one of the people on the IIS team has made an awesome PHP manager for IIS 7.x:
When PHP Manager for IIS is used, editing of the php.ini is pretty much redundant.
It offers recommendations for settings, as well as being able to edit PHP options and enable/disable extensions directly within IIS Manager.
I highly recommend trying it out if you're using IIS with PHP! I just used it to setup PHP 5.3.4 on Windows without a hitch.