I actually never used any PHP framework, I think it's more usefull to do everything by myself. However I read some articles about PHP frameworks and I'm sure the best one is Zend framework; The only problem is that it doesn't support AJAX, but you don't need it, so it's perfect for you.
You can download it here:
http://framework.zend.com/download/latest

Bye

PS: Sorry for my bad English, I'm italian and I'm still learning it.