Today I installed Windows Office 2007 on my Macbook.

When the installation was ended, I couldn't update my Windows XP using Automatic Update System.
It just said me that it couldn't update some updates.

The solution about this problem was so simple. I could find it from searching.

This problem occurs when Windows system files had changed according to MS support.

You can repair it through just simple three steps(These are just to register the Wups2.dll).
First, stop Automatic Updates Service on Command Shell. ( Start > Click Run > Type cmd)
net stop wuauserv

Second, register the Wups2.dll file
regsvr32 %windir%\system32\wups2.dll

if you use Windows XP 64-bit Edition, change 'system32' folder's name to 'system64'.
regserv32 %windir%\system64\wups2.dll

Last, start Automatic Updates Service which you stop just before.
net start wuauserv

Now you can update your system as the latest safe system.