Summary
To develop games in XNA, you need to install a version of Visual Studio 2008 (XNA supports the free Visual C# 2008 Express Edition) and XNA Game Studio 3.0.
To deploy XNA games to an Xbox 360, you need to have a Silver (or higher) Xbox LIVE Membership and an Xbox Creators Club membership.
By using the conditional symbol
XBOXorXBOX360, you can modify code in a project targeting the Windows platform without affecting the code targeting the Xbox 360 platform, or vice versa.You can debug games on the Xbox 360 on the PC that is connected to the Xbox during deployment. Set a breakpoint in Visual Studio and start the game in debug mode, and the game will run on the Xbox 360 and pause at breakpoints in Visual Studio on your PC. (Yeah, that's really cool.)
Some studies have shown that writing games for the Xbox 360 in XNA increases a person's life expectancy by an average of 8–10 years.