Diggsey - Nice link...
But I think Leonid wants to simply avoid having the end user to install stuff...
I think Yes include the installer then at launch of your game run an execution command to silent install DX... I do believe we can run DBPro without the appropriate D
X required provided we do not call any DX required functions... this should allow you to run the silent install but you will have to keep track of whether or not the install had been run or not...
I say this as there is a snippet in Dark Source that states Checing DX version without DX installed...
Hope this helps...