You can connect to a SharePoint Calendar through Outlook 2007. This will enable you to add and delete appointments from the SharePoint Calendar in Outlook 2007.
To learn more about connecting to a SharePoint Calendar through Outlook 2007, visit:
http://office.microsoft.com/en-us/outlook/HA100819871033.aspx?pid=CH101032731033
This option is not available for Outlook 2003.
