MSN Messenger can be tough to fully remove. Here's a start:
To disable MSN Messenger, there are a couple of things you can do:
In the system tray, double click the (presumed) green man icon. The MSN
Messenger window appears. Go to Tools, options, Preferences. Uncheck the
"Run this program when Windows start" box. Most of the time, this isn't
enough though.
In Outlook (XP), you can go to Tools - options - other. Uncheck msn
messenger.
With Outlook Express, go to Tools, options, General. There's an option in
there too.
MSN Messenger is tied in closely with OE. There is a reg hack to avoid
having MSN starting when OE loads.
Start - Run - Regedit. Drill down to here:
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Outlook Express]
In the right pane, right click and choose New - DWORD Value.
Name it Hide Messenger.
Give it a value of 2. You might have to reboot your machine
for the changes to take effect.
You could also use the group policy editor (Start - Run - gpedit.msc), and
find the setting in there (under Administrative templates - Windows
components - Windows Messenger), and disable it from there.
Good Luck,
Patrick Pitre