Simviation Forums

OK, I am now getting closer to taking the plunge and buying FSX, however, being somewhat careful with my hard earned, this brings me to a question. I have noticed on Amazon (UK, USA and Germany) that there is always the possibility to buy second hand or to get really lucky with ebay. Now it is my understanding that one must register the software when you have installed it. If I was to buy a second hand copy, would I meet up with any problems regarding the registration. Would the system (Windows registering people) think that it is pirate version due to trying to register it twice. I do not want to shell out only to have to buy a key from Windows or find that I cannot use the software.  

Matt