Unless you live in a place with lots of software/ tech companies then computer networks and data communication is the most important (bear in mind I am no professional and this is all coming from a random guy on the internet). 'IT Guys' are employed by most companies now and most of what they do is Network Admin. Other jobs are usually shorter-term (programmer for example) and harder to find.

My father's company employed a team of programmers to write a property browser with custom GUI and internet access etc. They had the job for 6 months, but the network admin/IT Guy will have a guarenteed job for a long time.

Of course I am a random guy off the internet who will probably be pointed out to be wrong within seconds of hitting reply.

Sounds like you've answered your own question then :)

If you're not sure, just ask yourself why not any of the other four? What would you expect to gain from bioinformatics, computer security, parallel systems or artificial intelligence? If it's a job you're aiming at you need to consider whether any of these other fields is as likely to get you a job.

Let me drill it: Parallel Systems. Do it, learn it well. That is of the most importance (based off of all other ones)for potential employers. Yes networking can be important, but without a server or client written in parallel it becomes close to useless. Computer Graphics, pretty close to applied linear. Nothing that can't be taught pretty quickly (at least basics).

Parallel systems comes into play in all of the above mentioned areas, and there are quite a few special things to work around (locking data and the likes, also communication is a huge one).

The programming languages class at my school gives the oppurtunity to create a compiler or interpreter (both can be useful to understand). Also it looks at many other languages and different types, all of which have their uses and strengths and weaknesses. I'd suggest this type of class to anyone who would like to get a better grasp over the why's and what's for languages (these must be discussed to create a compiler).

Also another reason to not do computer graphics: most college computer graphics classes will only go over transforms, getting triangles on screen (and textured) and thats pretty close to it. They will go through some of the math, but a lot of the shader (which many people associate with graphics programming) isn't hit upon. This may be different from your school but I highly suggest Parallel and Programming languages.