...because D3DX9_30.DLL was not found. re-installing the application may fix this.

I know this error has been around for other people...is there one step I am missing? When Decal installs, it asks for the AC install directory, I don't remember it doing that in the past. I have re-installed AC and Decal maybe 3 times and I keep getting this. I am running XP and I just re-installed XP on the computer. AC runs fine without Decal.

That's DirectX it's saying that is not installed. (Look for the DirectX download at the Microsoft Downloads ..)

But it is...I ran a hotfix to fix that too.

You need to install directx 9. There's a link to it in the sticky at the top of the forum that tells you all of the required stuff.

Well that fixed it. Thank you!
...for extra credit does anyone want to explain why dxdiag showed me with directx9 installed?

If you look at a Decal export, you'll see that there are multiple files that make up DirectX. If you're DirectX 9 isn't current enough, it won't have the files Decal needs. So it would show DirectX 9 installed, but Decal wouldn't work.