Of the drive can you go back. That is, an image of the drive you can restore from.
And yes, this is where many discover activation has "teeth."
I bought a refurbished laptop recently and had trouble getting it on line. It was suggested that administrative settings were blocking efforts to get online. It was also suggested to me that I try doing a repair/dynamic install of the OS (Windows XP Home). I have a store bought copy of Windows XP that I used when I built my desktop a few years back. I used this copy to do a dynamic install over the OS already on my laptop...then came trouble. I was not able to active Windows. Stupid me didn't realize that you are only allowed to use a retail copy of XP on ONE machine. Oops. My question now is, how can I roll it back so that I can at least access my files? Is there anyway to go back to the version of XP that was already on my machine or will I have to purchase new activation codes for my retail copy of the OS?