DX10 doesn't play DX9 games?

[phreak0ut]

Having installed Vista Ultimate, I wanted to check out how good DX10 renders graphics. I installed COD 4 and when I run it, I got the error: "File d3dx9_34.dll not found or corrupt. Reinstalling the application might help" I found that this problem occurs if you don't have DX9. I installed DX9 and voila! The game works. Is something wrong with the OS or DX10 doesn't support DX9? ( I know this question sounds n00bish, please excuse me )

[gxsaurav]

Install the latest DirectX 9 runtime from Microsoft.com

[BBThumbHealer]

^ DX 9 and DX 10 Both on a single OS [ vista by default has DX 10 ] ? howz that possible gx ?

[gxsaurav]

All hail MS for this

[BBThumbHealer]

Originally Posted by gx_saurav

All hail MS for this

[clmlbx]

ya,you will have to install dx 9,. as an example when you will install nero 8 .which needs dx 9.............but having dx 10 in vista it still shows to install dx 9 ..if you don't install dx 9,........ you cannot install nero 8..........