If you use Google to search for "Judaism," "Jewish" or "Jewish people," the results are informative and relevant. So why is a search for "Jew" different? One reason is that the word "Jew" is often used in an anti-Semitic context. Jewish organizations are more likely to use the word "Jewish" when talking about members of their faith. The word has become somewhat charged linguistically, as noted on websites devoted to Jewish topics such as these:
http://shakti.trincoll.edu/~mendele/vol01/vol01.174
http://www.jewishworldreview.com/cols/jonah081500.asp