Very little in certain contexts; unfortunately a whole lot in a few others. If your plan is med school or some (not all) other graduate programs, or working for certain big-name firms, a high GPA is generally a requirement. Freelance writer, not so much! Also, once you have entered the job market and have a proven track record of competence, it is far less of a factor. Talk to the nice folks at the Career Center (bit.ly/BC-career) if you want more detail on how your grades might affect your career.