Not an English major -- MIS Major with English minor, is that good enough?
I see no reason why not, but you better make damn sure that the quote really does tie everything together, is perfectly on topic, and isn't just some mildly related quote you think is cool.
My girlfriend is an English Major, graduate from UC Berkeley, and she says, NO! It is considered a floating quote. It would serve better in the middle of a sentence and/or paragraph.
What I generally do is open the paragraph with a leading sentence, follow with a contextually correct, but short quote and follow with supporting/closing sentences. From my experience professors hate long quotes so I try to find something as concise as possible.
Again, I am not and English major so take it fwiw.
Edit: Quotes are not filler to make paragraphs look pretty. They are there to prove that you understand the material you are discussing. You show this with a quote of relevance and substance.
i went back and forth with her until i proved myself correct on another issue. i believe you can end with a quote just like several stated above - it has to be a damn good quote, relevant, and correct.
03 DSG - na my g/f is a little better looking than that ;-), it's a little philly named Taylor Bow. i used it for the avatar when i first signed up and haven't changed it.