Older versions of AP Prep Books

<p>Is it OK to use older editions of AP Prep books? What major changes have there been on the US history and English Language tests since 2004? because I am planning to buy a used prep book rather than the new 2008/09 ones</p>

<p>Barron's How to Prepare for the AP United States History (2004) ISBN 0764123386 </p>

<p>And</p>

<p>5 Steps to a 5 on the Advanced Placement Examinations: English Language (2001) ISBN 0071377204</p>

<p>I was wondering about that too… except for Calc (2005/ 2006) instead</p>

<p>Can anybody help us??</p>