I've started reinstalling XP on my iMac after my fling with Vista RC1. It's got to the point where I have to enter my product key, that would be fine... If I hadn't left my damn certificate of authenticity at home when I came to uni . I called my mum to ask her to look for it, and she can't find it anywhere. Is it safe to turn my computer off in it's current state and carry on the installation when I've found my key?