For Windows XP Home Edition use "The registry edit & For Windows XP Professional you still use the option had suggested which is:

• Click Start
• Click Run
• Enter gpedit.msc in the Open box and click OK
• In the Group Policy settings window
o Select User Configuration
o Select Administrative Templates
o Select System
o Select Ctrl+Alt+Delete options
o Select Remove Task Manager
o Double-click the Remove Task Manager option

Keywords: Task Manager in Windows XP,Enable Or Disable Task Manager, Windows XP Home Edition