This in-depth tutorial runs through all of the neat and wonderful things you can do with PIX to help debug your XNA applications. In order to help you make use of PIX, it explains the relationship between XNA and native D3D9 and even provides a few helpful tables for easy conversions between managed and native types. 6 exercises (with source code) are included to demonstrate common tasks you can perform with PIX.
Download it here (includes a word document and sample projects)
Updated 2/27/2010 – added steps for viewing the device state, and specifying a layout for a vertex buffer