Stopping MS Messenger from running.

I have a system with a number of users who access the machine each day.
I want to disable or turn off the running of Ms Messenger for most users
(the users either do not like the product or are just not interested).
However, I have one user who wants to use this product.

I do not want any Messenger components running in the background sucking up
resources for those users you do not want this product. Overall we find it to
be a terrible waste on system resources and just annoying.

Thanks for the assistance