In Add/Remove Programs within the Control Panel, a list of installed applications is displayed for the purpose of easy removal. In the event that an application is actually removed but still showing up in Add / Remove please perform the following to remove an entry:
Download and install TweakUI from Microsoft for XP.
To start TweakUI, use the TweakUI shortcut in your Start Menu (it's no longer found in Control Panel), or run \windows\system32\tweakui.exe.
Optionally, one can perform these steps manually using the steps below.
Run the Registry Editor from Start->Run and key in REGEDIT.EXE and click ok
Open HKEY_LOCAL_MACHINE\ SOFTWARE\ Microsoft\ Windows\ CurrentVersion\ Uninstall, and remove any unwanted keys under "Uninstall."