The end of the world? No... just the next day.
Be prepared to actually install DX9!
Published on February 12, 2007 By Lotherius In Games
Turns out that Vista's DirectX 10 is not fully backwards compatible with DirectX 9, and Vista does not ship with the components required for all games that utilize DirectX 9.. Therefore, if you get any errors about missing DLL files from games when you try to run them in Vista (such as Medieval 2: Total War), then you'll have to actually download and install DirectX 9!

Just in case you need to do so - here's the link as of Feb 2007: DirectX Runtime Files

Comments
on Feb 12, 2007
I did have the Company of Heroes install ask me to install dx9c, which I did. However DX diagnostics says I still have dx10 installed,

Question; Have you heard why Vista shuts down you hard drives on a restart, and is there a way to make it stop? I thought it had something to do with the new power management stuff but I can't find anything to change.

I checked the EVGA motherboard forums and it only does if your running Vista not xp so it's not the motherboard.