Outlook Web Access Light is for those who will be using Outlook Web Access for more straightforward tasks, such as checking email and looking up contacts. This version is best for those with slower Internet connections. The Light client provides fewer features and is sometimes faster. Use the Light client if you are on a slow connection or using a computer with unusually strict browser security settings or if you are just doing a simple task (checking your email, for example). OWA Light supports most browsers such as Firefox and others. However, Internet Explorer is recommended.
The Outlook Web Access Premium client offers additional features, similar to the advanced features you might use if you have Outlook 2003 or 2007. This version will be useful for more advanced tasks (creating task lists, setting up reminders, etc.). The Premium features are present in Internet Explorer 6 or later. Therefore, only those with Internet Explorer will have an option between the Light and Premium clients. When using Internet Explorer 7 (IE7), you will automatically be logged into OWA Premium; if you'd rather use the Light version, you must choose this option from the login screen. Users with browsers other than IE7 will be automatically logged into OWA Light by default, as OWA Premium is not supported.