I usually set error_reporting to E_ALL when developing (forces you into good coding habits). When upgrading to PHP 5.3, a lot of “Deprecated” messages started showing up in some external software, though (things like CakePHP, WordPress, and Joomla). Since I’m not about to touch that stuff, it’s far easier to simply lower the error reporting level in the short run.
Using the php_admin_flag, this is easy, once you translate the PHP constants into integers. In the virtual host configuration (located in conf/extras/httpd-vhosts.conf in the latest version of WampServer), just add something like this:
php_admin_flag engine on
# choose the one you want:
# This is for E_ALL & ~E_STRICT & ~E_DEPRECATED
# php_admin_value error_reporting 22527
# This is for E_ERROR
# php_admin_value error_reporting 1