Problems installing as Administrator on a Vista Workstation

Hi, I am currently working on network that has a server and four workstations. I am trying to install a program to a user account that does not have admin rights. I only want this person to have it and no other user on this system (some workstations have more than one user). I tried running the setup.exe as “run as administrator” but it still comes up saying the rights are not there, but it is not asking me for my admin login. Is there something that I am missing or is it just Vista being difficult?