Is BS in microbiology better than BS in biochemistry for an Immunology grad school/career

I am deciding between a BS in microbiology and a BS in biochemistry to declare for undergraduate studies. However, I would like to pursue a career in Immunology (and perhaps study it in Graduate school). I was wondering which of the two is a better "lead-up" to immunology.

Also, can someone explain to me what the pre-med track is? I would like to do the pre-med track (since people are telling me I should do it) but what sort of requirements do I need?

I think you'd be ok with either major, but I'd go with biochemistry. The actions of the immune system are biochemical and depend on antigens, antibody formation, macrophage activation systems, and all of this involves protein structures on cell membranes and hormonal or antibody action on a molecular level, but there is also a case to be made for microbiology, since you'd be studying all of the white blood cells, and stem cell antibody formation in the bone marrow. I think it might be based on which study you are more drawn to as an undergrad.
Pre-med is really a human physiology emphasis in undergrad, including some pharmacology studies as well. If you are in high school and they are available to you, take AP biology, AP chemistry and AP physics if you can, but definitely AP biology and regular chemistry and physics at least. Also, ask the guidance department about math requirements. I've been out of school for quite a while and I'm sure things change, but I never had to use a lot of math in either undergrad or grad school, and I graduated with a BS in biology with a chemistry minor, then I got a Master's Degree in human physiology and began my phD in cardiology. I couldn't finish my thesis because of medical problems I developed, but I have the classroom credits. Cardiology involved a little algebra, but I didn't feel mathematically overwhelmed at any time. I had two years of algebra, a year of geometry, and a year of calculus in high school, and that set me up well for my future classes.