The Windows Phone 7 Developer Tools package includes everything you need to write awesome applications and games for Windows Phone 7.  All of the tools included in it are absolutely free.  You can download them here.

The following is installed with the download:

  • Visual Studio 2010 Express for Windows Phone – Free edition of VS 2010 for Phone development.
  • Express Blend 4 for Windows Phone – Free version of Blend for Windows Phone 7 Development.
  • Silverlight for Windows Phone 7 – Rich framework for building great applications for Windows Phone 7.
  • XNA Game Studio for Windows Phone 7  Rich framework that enables you to build great 2D and 3D games for Windows Phone 7.
  • Windows Phone Emulator – A hardware accelerated emulator that allows you to run and debug your applications and games without requiring a phone.
  • Phone Registration Tool – When you get a device, this allows you to “unlock” the device so you can run/debug your application on it, using your Marketplace account.

All of the above tools and frameworks are packaged into one setup, and everything is free.  If you already have Visual Studio 2010, the setup will also add support for Windows Phone 7 development and projects to your full Visual Studio 2010.