I graduated in 1998, B.S in Computer Engineering with a 3.6 GPA. No biology classes. My electives were in economics (minor in Economics). Now I want to study for the MCAT and apply to Med School. My question is: Does my 15-year-old college degree meet the requirements to enter med school? I don't want to make the investment (time + money) to take the MCAT and later find out that I am not eligible to med school due to my college degree. Can the fact that my college degree is old (1998) be a problem? Am I lacking biology classes? Or if I do well on the MCAT the med schools will not have a problem with it? I understand that every med school is different and the top ones will consider even the color of your shirt, so let's consider an average med school for the question.
Spend some time reading around, a lot of the basic information you need to get started can be found with some simple searches.
First, yes, your BS is fine to fulfill the requirement for a bachelor's degree to apply to medical schools. Your GPA is in the competitive range which means you don't have to worry about repairing it.
Second, you need a total of 1 year general chemistry, 1 year organic chemistry, 1 year biology and 1 year physics, all with lab. If you are missing any of these, you will definitely want to take them before you take the MCAT. Even if you took some of them back in the 90's, you probably would benefit from re-taking them so the information is fresh for the MCAT. Some schools have additional course requirements, and classes like Biochemistry, cell biology, microbiology, genetics, anatomy and physiology, etc. can be useful on the MCAT and help to show you are a capable student.
Third, you will probably want to take at least a few semesters of classes and get A's to show you are still a good student. The pre-reqs are the first ones you should take, and any of the additional courses if you have extra time to fill/money to spend. A medical school might be less eager to accept someone who hasn't been in a classroom as a student for over a decade, even if they have all the pre-reqs done.
Fourth, welcome, let us know if you have any questions. In the meantime, start some clinical volunteering and doctor shadowing if you haven't done so already, both to know for sure if this is what you want to do and because it is expected by admissions committees at medical schools. Good luck!