VNC is an excellent program for remote access, support, controller.
http://www.realvnc.com/
The free edition covers all of the basics you would need and then you get the option of using the 'personal' and 'enterprise' editions. This is a very useful ad free simple program.
Configure the server side application and client side application and away you go. The install package and running packages (once installed) are very small and have little to no impact on the general day to day running of workstations.
The free edition provides basic password authentication and then as you progress through the additions (if you wish to) you get the option of NT Authentication and encryption support.