[quintex]

If you have the time to join groups that you find interesting, but are not directly related to your topic of study, do it. You will spend the rest of your career increasing your skill set in the domain you chose, but university can be a unique chance to get to learn from all the other domains. In my experience, and your milage may vary, nobody asked about my grads after I graduated. The skills I gained by joining groups outside of CS helped me go much farther than spending that extra time studying I think ever could.