Removing messenger in XP can be made easy by going here
click on  "Remove Windows Messenger" and click on download .

http://www.kellys-korner-xp.com/xp_messenger.htm


If you prefer to remove Windows Messenger manually, click Start, Run and enter the following command:

RunDll32 advpack.dll,LaunchINFSection %windir%\inf\msmsgs.inf,BLC.Remove

Use manual way only if you know what you are doing.
If you are a novice,the tool is simple.