As for the Purpose Driven Life, it is crap.
http://www2.pcanews.com/editorial_opinion/monthly_umpired_debate/print.taf?topic_paper_ID=48
http://www.bereanbeacon.org/articles/rick_warren_purpose_driven.htm
http://www.monergism.com/thethreshold/articles/onsite/purposedriven2.html
(the book demeans the very nature of God)
http://www.opc.org/new_horizons/NH04/05d.html
How many copies has Piper sold?