On 5/27/2008, after applying Service Pack 3 and subsequent updates to a fresh install of Windows XP Professional Service Pack 2, the following files and information were found in %windir%\system32 with the respective file versions and dates modified.
msi.dll 3.1.4001.5512 4/14/2008 5:42 AM
msiexec.exe 3.1.4001.5512 4/14/2008 5:42 AM
msihnd.dll 3.1.4001.5512 4/14/2008 5:42 AM
msimsg.dll 3.1.4001.5512 4/13/2008 9:09 PM
msisip.dll 3.1.4001.5512 4/14/2008 5:42 AM