Removing Windows Search 4.0 Without It Showing Up in the Add / Remove Programs Control Panel

With Microsoft’s recent release of Windows Search 4.0 for Windows XP, a number of users who had it installed complained about their system becoming rather slow and they wanted the old search functionality returned.  In most cases, a simple uninstall via Add/Remove Programs restored the search functionality to its previous incarnation, but in one particular stubborn case, “Windows Search 4.0” did not show up in Add/Remove programs while Windows Search 4.0 was clearly installed (toolbar and the taskbar icon were present, as were the individual processes).  Unfortunately, C:\Windows\$NtUninstallKB940157$ was not present, either, so a manual uninstall could not be performed.
The solution was to forcefully remove the following registry entries, via regedit:

• HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Updates\Windows XP\SP3\KB940157
• HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\KB940157

Once those were removed, manually installing Windows Search 4.0 from Microsoft got the add-on to install properly, complete with an entry in Add/Remove Programs.  Finally, selecting “Remove” from the Add/Remove Programs control panel for “Windows Search 4.0” did the deed and removed it from the system.