On the Web, you can find a wealth of information that will help you jump-start, complement, and expand your knowledge of XNA game development. Here, I have compiled a short list of online resources you can check out at your leisure.
These bloggers have written about many XNA development topics:
Game Theory, Dan Waters (http://www.danwaters.com): As an academic evangelist, I travel the United States, showing Microsoft technology to students and faculty. My blog often covers gaming-related topics. You can find screencasts, source code, and more.