Checking your directx version is actually quite simple and in fact very much the same no matter what version of Windows you are using.
However, I will be providing you with a quick picture guide on how to Check Your Directx Version On Windows 7 because this is a new OS and people will soon start asking.
Windows 7 comes with Directx 11, but if you must make sure, this is how to do it.
1. Go to the Windows Start Menu
2. In the search box type in dxdiag and hit enter
3. A box may or may not appear . If it does, click yes. (screen shot coming soon…I need a fresh computer to get this message)
4. Check out the information on the window that comes up and you will see the Directx version at the bottom. (you can click on image to see it full size)