If you never activated the software and were not asked to activate it on install then someone illegally gave/sold you a disk for a multiuser license. All single user licenses for CS3 require activation. Alas, you have been snookered. It is the person that sold you the software that was supposed to fill in the transer of ownership form not the buyer. I'd recommend contacting Adobe Customer Service to see if you can legally use the software.
Actually, I disagree that I have been "snookered". After posting the original inquiry, I talked at length with a very knowledgeable and helpful Adobe customer service rep (can't believe any software company is providing this service, certainly not Autodesk). Basically, for $150, I have purchased genuine Adobe software, properly activated it, and have received multiple updates. The only thing I am missing by not transferring the license is official help from Adobe. In 2009, I think that if I was running Adobe that I would not provide users anything beyond e-mail help after the first 90 days, and nothing after the first year. As such, I do not expect Adobe to provide technical help ad infinitum to me and anyone else who might use the software after the original buyer.
Therefore, I have purchased legal software for a fraction of the original cost, properly activated it, and Adobe is providing updates for free, and I am happy. Technical help? That's what the forums are for.