Top business schools are nationally (and perhaps internationally) known brands. A diploma from a Top Rank business school, a 2nd Rank, and perhaps 3 or maybe even a 4th rank school, will give you a “wow factor” during an interview. But this is true ONLY for the first job after business school. For the rest of your career, your resume will be more impacted by your job experience than your business school.

Recruiters and managers read the same rankings of business schools that you read. These top rankings help a school's reputation and repeated appearance in Top 10 rankings can have a huge effect on the “wow factor”. Therefore we can consider those schools that almost always appear in the Top 10, to be the Top Rank schools and these will most likely have the biggest “wow factor” and will help you most in the interviews for the first job after business school. Lower ranked schools usually have less of a "wow factor". Unranked schools may have no "wow factor" at all, or the "wow factor" may be regional. That is, some business schools are very well known in the local community and may help you to find a job in the local area. However, outside of the region, it is possible that no one has heard of the school.

Almost always in Top 10 (Top Rank)
Harvard
Stanford
Wharton (University of Pennsylvania)

Usually in Top 10 (2nd Rank)
Dartmouth
MIT Sloan
Northwestern
University of Chicago

Often in Top 10 (3rd Rank)
Carnegie Mellon
Columbia
Cornell
UC Berkeley
University of Michigan
University of Virginia
Yale

Sometimes in top 10 (4th Rank)
Duke
NYU
University of Virginia
UCLA
UNC Chapel Hill

International Business Schools
Insead
IMD

What does Business School give you:
1. ‘Wow Factor’: If you graduate from any of the Top Rank or Second Rank schools, you will walk into an interview with a ‘Wow Factor’. Interviewers will automatically assume you are bright or special, whether or not it is true. This ‘Wow Factor’ is yours to lose. If you have a bad interview, the ‘Wow factor’ can be lost. After your first job, your work experience will have more of an impact than your business school.
2. Access to Alumni: Many top business schools have a very loyal alumni network, and some of the alumni are likely to be top managers from your industry. Schools often compile databases of alumni catagorized by industry and job title. You can use this database to do your networking. Mentioning to Alumni that you are currently studying at their business school is a great door-opener which can help you land an interview. Some may not respond, but the alumni-network is a much under-ultilized resource.
3. A Diploma: Many people go to business school because they assume that an MBA will give them a career.  Remember that, unlike the practice of medicine or law, the practice of business does not require a license. Someone with better experience and no MBA may be more attractive to an employer. Not all MBA's are the same. While a top business school will give you "Wow Factor" an MBA from an unknown university or an unaccredited university may be of little help to your career.
4. Classmates: Sometimes your classmates can be helpful to your career, but this may depend on the industry you choose to go into. If you are going into the oil refining industry, probably only those people from your class who are also in the refining industry will be helpful to your career and there may be few of these in your class. On the otherhand, if you go into banking, possiblity many of your fellow classmates will end up there and the ones that rise to the top, can be helpful to you.
5. Access to Recruiters: Somewhere around the middle of your first year of Business Schools, recruiters may come to find summer interns. In the middle of the second year of business schools, recruiters may come to find the best young MBAs to offer jobs to. Recruiters can not visit every school. However, there tends to be a link between some companies and some business schools. The higher ranked schools, will attract recruiters from the most prestigious companies. Lower ranked schools often only attract recruiters from local companies.
6. Business Skills: Will what you learn in a top business school transform you into a better business person? This is highly debated. Critics of business schools claim that what is taught is mostly theoretical and often not useful in business practice. It should tell you something that many very successful business people (Bill Gates from Microsoft is the most common example) never attended business school at all. As Jeffrey Pfeffer and Christina T. Fong from Stanford Business School point out, Business School "students learn to talk about business, but it is not clear they learn business."

Go to the highest rank school possible.
It is very possible that the quality of the education from a low ranked business school will be as good as or even better than the top rank business school. But the sad truth is, education is not the only reason, and perhaps not even the most important reason, to attend business school. For many, the most important reason to attend business school may be the ‘Wow Factor’ or the job recruiters that come to the school. The Wow Factor and the right recruiter could help you to land an amazing job after business school and this can be the beginning of a great career. 

Many students who attend a business school with no "Wow Factor", find that they have invested two years of their lives and a great deal of money, only to return to a similar job and a similar pay that they had before business school.

Whatever business school you attend, make sure it is accredited by a well known accrediting agency such as AACSB. Less than half of the schools which give MBAs are accredited and you may find an MBA from a non-accredited university to be useless.