I currently own a macbook which I am happy with. I will be starting CS coursework in august, is it ok to buy a netbook just for programming purposes. The largest file would be the compiler; I do not see the actual programs taking up that much space. Thanks.
compiler, libraries, and headers. That can take up a decent chunk of space.
Yes, it is OK, but expect the MacBook to work better 
My MacBook Air is the best computer I have ever owned. Very light, fast, reliable. It is far superior to any laptop, notebook, or netbook I have used or owned.
My advice: Look at the full Computer Science syllabus in great detail and also telephone the University Department for advice. If the course has a M$ bias you might need a computer inferior to a MacBook which runs a specific version of M$ Windows.