Shoutbox

Matty Bix, since use Windows XP, I suggest you set up accounts up for each user on your computer.
This way everyone who wants to can have MSN Messenger settings, and Plus totally isolated to their own Windows account (it is kind of like having your own computer in a computer).
You won't need loads versions of MSN Messenger running at once for each person on the same screen, you can have it cleanly set for one in each account. Go to Start > Control Panel > User accounts and set an account up for each user.
This way is a lot cleaner and you can have your own locking messenger settings that will for sure, only lock in your MSN Messenger in only your windows account. With the tool I showed you before you can set your own default browser, so that StuffPlug-NG will only open the links you click on in your default browser.

I understand that what I said may be unclear if you are new to setting up windows accounts, if you are unsure just ask and I will be personally happy, as will many other members here, to help you.