http://www.google.com/search?hl=en&q...=Google+Search
Theres 944,000 reasons for you. :P
Ironically, doing the same search with different names of popular javascript libraries offers more results. (IE, "Why prototype is better" got 15 million results...)
I don't have any actual Jquery experience, but have heard excellent things about. Some of the articles on that first google link are actually good too.