You can read the first book in the Ranger's Apprentice series, The Ruins of Gorlan, for free!
Then follow this link:
http://www.scribd.com/doc/10330799/Rangers-Apprentice-The-Ruins-of-Gorlan
The Ruins of Gorlan is the first book in the series and I devoured it in less than a day of reading! :-)
If you like books like J.K. Rowling's Harry Potter series or the Pendragon series by D.J. McHale, you will LOVE the Ranger's Apprentice series too! And I'd bet your kids would as well....