when you using windows xp, you might want to install office 2007, but how many times your office 2007 installation has been roll backed, displaying series error message looks like below.

"Microsoft Office 2007 encountered an error during setup. The Windows Installer service cannot update one or more protected Windows files"

you know there is a solution for you, this one is a quick method and results are guaranteed.please do as follows.
• first insert your windows installation CD to CD-ROM
• go to the I386 folder and locate the Cab file named FP40EXT.CAB
• copy the cab file to the hard disk
• now extract the cab file
• in the extracted folder find the fp4autl.dll file
• now copy this file to the following location
• C:\program files\common files\microsoft shared\web server extensions\40\bin\
• that's it, now restart your office 2007 installation.