If you do not need to reactivate with Office 2003, that is probably because your copy of Office 2003 does not require activation in the first place.
Windows Vista and Office 2007 are different. All versions require activation. (If I am wrong please correct me. However, I think it is obvious that your copy of Office 2007 require activation to work.) Your copy of Office 2007 will demand reactivation since the hardware presented to the software under Parallels is different from under Boot Camp. There is no way out of this. If you reactivate Office 2007 inside Parallels, most probably when you boot Windows natively and run Office 2007 you will be again required to reactivate, and so on. Sooner or later Microsoft will deny you reactivation on suspicion that you are a pirate.
That is why I avoid software with activation as far as possible. I use a Corporate version of Windows XP, and Office 2000, both of which does not require activation.
Last edited: Mar 26, 2007