Gundrukbhaat, Biochemistry, Microbiology is indeed a very rewarding field of studies. It requires intense, hard work and patience. If you are focusing on financial reward right after your undergrad degree, then there might be some other options (Business??). Industry microbiology/Biotechnology is one of the fields that have been much talked about recently. Though you can get an entry level with a BS, however higher degree is preferred in all of the majors you listed. All majors ( microbio, molecular bio, biotech, cell Bio) includes basic research, product development such as vaccines, genetic engineering is another topic that has been highly talked about. In a nutshell, if you have passion for science, then go for it!! You are getting a head start by exploring pros and cons. Go to seminars at your school, talk to your professors, and work in their labs if possible to get hands on and know if it is something you wanna do in a long haul. There is intl. biomedical society banner in the right corner of sajha's homepage that may interest you. Good luck, Jyotsna