Installed Windows 7 Ultimate x64 instead of Professional x64
I bought a a serial key of Windows 7 Professional x64, but I accidentally have installed Ultimate x64. And I spent 2 weeks setting up my computer, installing soft-wares, games and other stuff. And now I figured out that the key of Professional x64 wont work on Ultimate. Is there any way to shift it to Windows 7 Professional x64 without affecting all the files and settings.