Useful tip for building WSS v3 Feature XML files
VS 2005 comes with an XML Editor that provides IntelliSense for XML based on a schema. To leverage this feature, add a new XML file in Visual Studio and select the Properties window for the XML. In the Properties window, select the Schemas property.
In the browse dialog box, choose Add and select the WSS12.xsd schema from the following folder: \Program Files\Common Files\Microsoft Shared\web server extensions\12\TEMPLATE\XML\wss12.xsd. Once the schema has been set, the XML Editor within VS 2005 provides validation and IntelliSense for writing XML.