To remove Windows Messenger manually, click Start, Run and enter the following command:
If you have XP SP1 installed then you will get an error. Just Click okay and it will complete the uninstall. Once you restart windows messenger will be gone!
Notice from BuffaloHELP:
What's not your own words should always be quoted. Source http://www.dougknox.com/xp/tips/xp_messenger_remove.htm This is your only caution note.