http://create.msdn.com/en-US/education/basics/developer_resources
This is your one-stop shop for information about developing apps and games
for Windows Phone. The links on this page represent the best available info for
Windows Phone developers from Microsoft and a variety of other sources,
including top bloggers.
If you'd rather dive right into coding, Create
Your First Silverlight Application for Windows Phone, Create
Your First XNA Framework Application for Windows Phone, or create something
more complex in Building
a Windows Phone Application from Start to Finish.
getting started