This is probably a reference to this clause, found both in Vista and Windows 7 eulas. Available here in various eulas, such as Vista Home Premium English and Windows 7 Home Premium English, found here:
microsoft
Searching the XP sp2 eula does not seem to contain a similar clause.
"6. POTENTIALLY UNWANTED SOFTWARE. If turned on, Windows Defender will search your
computer for “spyware,” “adware” and other potentially unwanted software. If it finds potentially
unwanted software, the software will ask you if you want to ignore, disable (quarantine) or remove it.
Any potentially unwanted software rated “high” or “severe,” will automatically be removed after
scanning unless you change the default setting. Removing or disabling potentially unwanted
software may result in
other software on your computer ceasing to work, or
your breaching a license to use other software on your computer.
By using this software, it is possible that you will also remove or disable software that is not
potentially unwanted software."