Just the installer/autorun throws a fit after finding speed.exe in the registry. Each version and it's launcher has it's own installed directory listed in the registry, along with unique registry data for the exe, dll's system file directories etc.. No need to worry about having issues luanching/changing settings/playing the game/saving etc. They both may use the same registry key "SPEED.EXE" but you can have two in the registry, the file locations and internal data will be unique for each application and no conflicts will occur untill you try to intall another NFS title that uses the same speed.exe registry key search, you will have to rename two of them..