Earlier today, I was clearing down an old PC in preparation to donate it to a worthy cause. I remembered that installing Windows XP on it had been a long process, so I just removed the data (nothing sensitive, so no need to securely delete anything), uninstalled the applications and hacked the registry to change the registered owner/company (look for RegOwner and RegCompany string values for various products throughout the registry but the main ones I wanted to change were the RegisteredOrganization and RegisteredOwner string values in HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WindowsNT\CurrentVersion as these are the ones shown in the system properties – the easiest way to find them is to look up the registered to values in the system properties and search the registry for the appropriate string).

Although various installers had left behind subdirectories which needed to be removed manually, there was one application for which the uninstall failed but repeated attempts resulted in an error – leaving behind an entry in the Add or Remove Programs Control Panel applet. I needed to know how to remove this entry and found the answer in Microsoft knowledge base article 247501 – it involved more registry hacking to find the appropriate entry in HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall but it did the trick.