Account Setup

Hey guys, newbie here......... I've actually been using XP PRO for a while now, but never had to worry about user accounts or permissions and groups because I was the only one using my computer. I now have that problem where people are using it and getting into files and running applications that I don't want them too. I have tried making user accounts with limited access but people just get around that by going into My computer and then program files, even the guest account can do that and run programs which they shouldn't be running. Guest accounts as well as limited users or any other type of users can also go into C:\Documents and Settings and select any user of choice and view all their personal files saved in their documents directory. I remember in 2000 that there was a way to RESTRICT USERS FROM SEEING OTHERS FILES AS WELL AS OTHERS INSTALLED PROGRAMS. I want people to have their own accounts, install and run their own things, and only see their own files............ How do I do this??? PLEASE HELP!!!!

you have to have to being using the NTFS file system, not FAT32

i am using NTFS......... any other suggestions????