It seems that I've made the wrong conclussion. You have also MSN Messenger 7 at home? Or not? If you have, then you only need to install the ink redistributables, instead of the whole plugin.
To only install the Ink redistributables, download them here:
http://kaonet.net/page.php?id=75
2) unzip the file to a directory of your choice. (do not run anything from within the zip)
3) go to that directory and start
setup.exe
4) make sure you have ticked the option "for all users"
5) reboot
/ 
