Arg! This is not what I want Tiger! *cry*

I want to secure the NTFS permission. My password are secure, my guest is rename, my service are dead, my locally policy setting are done. The machine I want to secure is a Terminal Server where 15-20 peoples log on. They run all their software from the Terminal. I want to secure that Terminal by changing their NTFS permission on folder/program terminal user don't need that Windows install!