Policies in Windows Server 2003

I have Win Server 2003, and a lab of 20 computers. I have tried to set policies for students to be able to change their desktop pictures, and for the start menu to show their most recently used applications. and I want to get rid of some of the icons there. I have gotten it to show the latest app, but that is lost when they use another. Please tell me what settings I need to change to fix this, and if there are any security risks involved. Can right clicking be enabled for them?
Thanks,
Lynne