Windows XP OEM preinstallation Kit Question

[Rainguy]

As a system builder I use this and the sysprep tool to reseal a system prior to giving to the customer. My question is, how do you reset the 30 day clock on the activation if you prepare the system but, don't sell it before 30 days? Also. I burn recovery disk image for the customer in case they botch their system. Does the activation date get set on to the image that if you try to restore after 30 days that it will not let you log into Windows?? Anyone have experience with this and any links on MS's site?