Call your school, find out exactly what you will be using. Plan your platform around that. Don't go for a Mac, because it is supposedly more secure than Windows, or Windows, because there is more software, or Linux, because it is free, until you know exactly what software you will be using. FWIW, some of our labs still run on Solaris.
And for CAD software, unless you really need portability, I think a desktop would probably run a bit better.