I am using WinXP, the 64-bit version on an AMD 64-bit machine. I have been using it for several months now. I recently noticed that MS had a security update for the 64-bit version, but when I tried to download it, I received an error message that the download file was valid but "is for a machine type other than the current machine". Anyone have any ideas why, or what I can do?(other than revert to the 32-bit version.)