And also I would recommend the book of F. Eady hands on Zigbee. Look at:

http://www.amazon.co.uk/Hands-ZigBee...7889618&sr=1-1

It explains the topic very well. I am reading this book and can say, the writing of Mr. Eady is top.

Also the XbeePro is a module that offers great range (up to 1.5Km)

Ioannis