Rakekniven, I'd have to disagree somewhat with your statement about karate and judo being on the decorative side of martial arts... Both can be devastating if the training is correct. I've known people from both who were skilled fighters (not just in competition). The question is: How is it taught? I've seen a lot of junk out there that called itself "karate" (or whatever), but really wasn't anything but a way to get students to part with their money (Choi Kwang-do comes to mind).
However, this is an introductory college course, not a fighter's club, and I think the instructor would probably teach it that way. In other words, I doubt that you'll walk in to a Kyokushinkai-style bare knuckle full-contact class - and even if you do, you probably wouldn't be ready for the "hardcore" training in the course of a semester. The first few months are necessarily dedicated to building a good foundation on which to build your skills. Whichever you take, don't expect to get more out of it than a few basic techniques & some exercise.
The question is, what do want to get out of it? If you want to learn the basics of how to fight in a few months, I wouldn't choose either. I think I'd pick boxing or wrestling (or Thai boxing, if they offer it) for that - they throw you in the mix a bit quicker.
If you're thinking about picking up a new lifestyle when you graduate (don't kid yourself - training is hard work, and it only gets harder as you progress), then I think I'd pick the one that I thought I was the least interested in - who knows, you may find you like it - and "save" the other for when you can settle into it. Then look for a good school that you can stick with for quite some time. It's a lot harder to unlearn than it is to learn.
Of the two, for a semester, I'd pick Judo. What it can teach about balance, falling, throws, takedowns, etc. would translate well into whatever you study later.