To be honest, rankings aren't very important, especially at the graduate level. Instead the important question to ask is whether you will get the training you need for the career you desire. Look carefully at each program without worrying too much about rankings. Ask:
- Is the institution a "real" college or university? Does it have accredited undergraduate programs?
- Look at the program itself -- the courses required. Will those courses provide the education you desire?
- What applied experiences are offered, if desired? Will these experiences give you the training you need?
- How many students are admitted each year and enrolled?
- What do graduates do after graduation (this is important) -- do they go to graduate school, get jobs in industry? Does this fit with your own desire?
- Who are the faculty? What are their research interests?
- Do your interests match faculty interests? Do faculty incorporate students into their research?
While rankings are useful -- it's the answers to these questions that really matter. Graduate school admissions is all about fit. From the program's perspective the question is whether your training goals match their training objectives. From your perspective, the question should be: Will this program offer the training you need for the career you want. Attending the most highly ranked program will do nothing for you if it doesn't provide the training you need for the career you want. Generally speaking, at this level, choice of programs isn't really about rankings - it's about choosing a program that will fulfill your needs for training.