Yii framework, if you like PRADO you will like Yii more! It is an MVC framework! It is very small! It provides tools for code generation, a good set of sample applications that you can get up to speed very quickly! You can use it to develop web services with build in support.
Yii -- a high-performance component-based PHP framework best for developing large-scale Web applications. Yii comes with a full stack of features, including MVC, DAO/ActiveRecord, I18N/L10N, caching, jQuery-based AJAX support, authentication and role-based access control, scaffolding, input validation, widgets, events, theming, Web services, and so on. Written in strict OOP, Yii is easy to use and is extremely flexible and extensible.
PHP 5.1.0 or above. it run on Apache on Linux and Windows
Mysql, support various databases via PDO,