This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
Ajax is best used when you want to updated small parts of the web page without forcing the user to wait through an entire refresh of the page. If most of the page needs to change then you're better off rebuilding the entire page.
I'm sure there are other rules, but this is a good one that applies in most situations.
Ryan Asleson<br />Co-Author, <a href="http://www.amazon.com/Foundations-Ajax-Foundation-Ryan-Asleson/dp/1590595823/sr=1-1/qid=1158926537/ref=pd_bbs_1/002-7412154-2924860?ie=UTF8&s=books" target="_blank" rel="nofollow">Foundations of Ajax</a> and <a href="http://www.amazon.com/Pro-Ajax-Java-Frameworks/dp/1590596773/ref=sr_11_1/002-7412154-2924860?ie=UTF8" target="_blank" rel="nofollow">Pro Ajax and Java Frameworks</a><br /><a href="http://taconite.sf.net" target="_blank" rel="nofollow">Taconite</a> Lead Developer