Add/Remove Programs Using RegEdit

If a program/application is still listed under your add/remove programs, then those entries can be removed using regedit by following the below methods

Manually remove programs from the Add or Remove Programs tool:

• Click Start, and then click Run. 
• In the Open box, type regedt32, and then click OK.
• In Registry Editor, locate the following registry key:
  HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall

• In the left pane, click the Uninstall registry key, and then click Export on the File menu. 
• In the Export Registry File dialog box that appears, click Desktop in the Save in list, type uninstall in the File name box, and then click Save.

Each key listed under Uninstall in the left pane of Registry Editor represents a program that is displayed in the Currently installed programs list of the Add or Remove Programs tool. To determine which program that each key represents, click the key, and then view the following values in the details pane on the right:
DisplayName: The value data for the DisplayName key is the name that is listed in Add or Remove Programs.
and-
UninstallString: The value data for the UninstallString key is the program that is used to uninstall the program.

• After you identify the registry key that represents the program that you removed but which is still displayed in the Currently installed programs list of Add or Remove Programs, right-click the key in the left pane of the Registry Editor window, and then click Delete.  
• Click Yes in response to the "Are you sure you want to delete this key and all of its subkeys?" message. 
• On the File menu, click Exit to quit Registry Editor. 
• Click Start, click Control Panel, and then click Add or Remove Programs. 

In the Currently installed programs list, verify that the program whose registry key you deleted is no longer listed.

Do one of the following:
If the program list is not correct in Add or Remove Programs, double-click theUninstall.reg file that you saved to your desktop in step 5 to restore the original list of programs in the registry. 

-or-

If the program list is correct in Add or Remove Programs, right-click theUninstall.reg file on your desktop, and then click Delete.

For more information check the article on Microsoft Support Site

Posted in: Add Remove Programs,PC Support,Technical Support,Windows XP Support