fixing users program acces rights

Hi Folks, I'm trying to find out if it is possible to
restrict or allocate users on the same pc when accessing
programs and folder from their log on. In other words I
want to be able to give access to one user for the
accounts software and folder and at the same time prevent
other users from seeing or using these resources. Is it
possble to customise what each user sees on their desktop
and restrict their access to the folders I don't want
them to see? I have mutiple users from diferent
departments that use the one machine in a school and I
don't want, for instance, pupils being able to see
financial records or employee details or to be able to
start the accounts applications.