Windows XP Embedded systems 2009

Hi,
I just have a few technical questions regarding Windows Embedded systems. Whenever I go to the arcade, sometimes see newer games (2005 and on) booting up on Windows. I've read online that they use Windows XP Embedded or Windows Standard Embedded 2009.
- What is the advantage of using this "embedded" software versus just booting the game on the full version of Windows XP?
- What would theoretically happen if arcade games used the full version?
- Would the arcade system board require more memory?
- Most home users (or all) play games on their PC (or Mac) through the full OS, and the games boot and work fine. So, what is really the purpose of Windows Embedded software for use in arcade games and other devices?
Thanks,
