@Seditious I've just had to install W7 on my desktop after a hardware failure and encountered similar difficulties. I eventually had to download the DirectX runtime - the so-called web installers didn't work.
Here's the link I used. The download is about 9
5MB. There may be a smaller download somewhere but this worked for me. The MS description of their web installer seems very misleading to me. I suspect it merely updates existing DX9 installations and therefore does nothing if you haven't already got it.
DirectX Runtimes
Edit Forgot to add that after you've downloaded that file you need to run it and extract the files to a folder of your choice. Then go to the folder, find the dxsetup.exe file and run that. That final step will actually perform the installation of DirectX
9.0c. As a final step I then ran the web installer again (just in case a few files needed updating) and now everything works fine.
There ought to be a simpler less convoluted way of doing all this but I couldn't find it.