Seriously Build Windows 8 Apps or space aliens will take over the Earth. Building Windows 8 Apps is cool, having the Earth taken over by Space Aliens is definitely not cool.
Fast and Cool
Seriously, I just loaded it on my main machine and it is AWESOME.
Just do it.
After you do a backup and recovery disk creation of course.
To really get started with DirectX go to http://www.directxtutorial.com/ and the $50 premium content is WORTH it.