I have 7 Professional retail box with 32 & 64 bit disks. I am running the 32 bit but would like to try the 64 bit. I have been given conflicting answers. As I have both disks am I able to run both 32 and 64 bit with the same serial number? The reason I use 32bit is so I can run old games but have now bought the lastest Doom which only runs on 64bit.