The 64 bit edition was written for 64bit PC’s. If you did not remember purchasing a 64bit PC, then yours is most likely to be a 32bit. If you open the my computer icon, then double click your c drive and you see 2 program files folders, one of which says program files x86, then you have a 64bit OS. If you only see one program files folder, you are running a 32 bit OS and you most likely have a 32 bit PC, which is more than adequate for most users. Here is a more in-depth explanation.