I wanted to install Microsoft Office 2010 on an old Windows XP (64 bit) laptop. I tried running the setup and I got an error saying that I needed Windows XP SP3. Now in case you didn’t know Windows XP (64 bit) doesn’t have an SP3. SP3 for Windows XP was only released for the x86 version of the OS.
So I tried running the XP Compatibility Mode. To do this right click the setup.exe choose properties and then choose Compatibility. Change the drop-down list to “Windows XP” then run the setup. I don’t think this is officially supported but it worked perfectly for me.