I graduated with a PhD in CS recently. Regarding the M.S. degree, grad schools usually offer two avenues: thesis track and project track. The thesis track is more research-oriented, and you have to publish some papers and have a good thesis report at the end. The project track is crap; basically you do some software programming to support the PhD students' projects, and in the end you write a project report that no one will read. Which one you choose is up to you.
Regarding the rankings, here is the latest rankings from US News.
http://www.usnews.com/usnews/edu/grad/rankings/phdsci/brief/com_brief.php
Here's a full list from 2002:
http://lazowska.cs.washington.edu/usnews2003/cs.htm
Don't worry that it's 3 years old; the rankings do not change much at all, at least not within the top-10. If you don't go to a top-25 school, you shouldn't even bother going to grad school at all.
I don't like the way US News ranks, because the rankings are based on three categories: theory, AI, and systems. AI is a tired topic that really should not have a category of its own. Systems should really be split into subcategories, because it subsumes databases, OSes, and networking, among others.