You don't need to install two windows 7 operating systems to use it at school and at home. You will be complicating the things, especially when the notebook belongs to the school.
In schools normally the admin locks the local admin account. All you have to do is put a request with your school teacher/lecturer/professor to ask the admin to create a local normal user account for you in Win 7 Ent. on the netbook. With this account you can login at your home with local username and at school with domain account. This way you will have two different profiles, one for school and one for home separated from each other.