so save me

I know this subject has been beaten to death..but..

I want a Mac but I don't know which one to get or if I should even get one because of possible compatibility issues or something? I don't know what I'm going to major in so it's not like I can check with a department and see what their requirements are. Are there any majors where I should avoid a mac?

Has anyone tried the new Macbook? What's the difference between the Powerbook and the Ibook?

Basically all I do on my computer is internet/chatting.. paintshoppro or photoshop.. wordprocessing and music. i don't play games so that's not an issue.

What can't I do on a Mac that I would have to get on a computer in the library to do, for instance?