No, msg plus! does not contain virusses it has an OPTIONAL sponsor.
Also you have MSN 7 and plus! isnt compatible with that yet so thats why you get these messages.
For full instructions on how to uninstall plus! see:
http://shoutbox.menthix.net/showthread.php?tid=21...d=203362#pid203362 (make sure you have your internetbrowser fully closed on uninstalling...from taskbar an systray also)