How do I prohibit AD user GP’s from affecting certain PC’s and not others?

I work at a high school and our student accounts have a GP that locks down XP machines that students logon to. The GP is linked to the user accounts OU. However, there are a few specialty machines that students need more or full access to, i.e. Yearbook designated computers. I was wondering if there is a way for me to do this with either GP or through the local policy on the PC’s itself. Any help would be greatly appreciated.