What course should I take for a networking, security or development job?

I just graduated with with a bachelors in information science engineering, and I am interested in a job role that relates to networking, security or software development. With no working experience (except for 6 months technical support at IBM, right after I graduated), what course (such as a Microsoft certification or CISCO course) do you think would land me my desired job at a good company? I'm planning to quit IBM this month, and would like to bolster my credentials so I'll get hired- which is difficult, otherwise, since most companies require relevant experience.