DIRECT X .... but which?

[mrlewp]

First , how do I even find which version of DirectX I have now. Recently had to do full recovery on HP laptop. Was using Windows 7 upgrade, but the recovery
reverted to VISTA. PC tech had to do it, since I couldn't get it to boot, following severe infestation.
Wound up back to Vista 32, as purchased almost 2 yrs. ago. Even tho' its a 64 bit processor. ........ off track, I guess.
I'm seeing news about DirectX 10. I used to get D'X update requests fairly frequently. But not so much on this "renewed" Vista, NOR on my XP pc, which ALSO went thru a complete recovery recently.
Would any video program requiring DirectX , let me know if it needed an update ? ... likely when it couldn't play a video file ? correct?
thanks.

[admin]

Start -> run -> dxdiag -> It should start the DirectX Diagnostic Tool and show the current version of DirectX installed (which for Vista, should be DX10 by default).

For Windows Vista and onwards, you actually can have multiple versions of DX installed at the same time, so DX9, DX10 and DX11, and whichever version an application requires, it will use the right version.

Normally, if an application, usually a game or a multimedia software requires a specific version of DX, it will come with it and ask you to install it, so there's probably no great need to install anything else unless something isn't working right. Also, for example, if the application was written for DX9, installing DX11 won't really help as the app will just use DX9.

Most games and applications still very much rely on DirectX 9.0 (9.0c should be the latest version - more info and downloads here).