I bought NFS Carbon and I run into the same problem as described initially. Whenever I tried to install NFSC, I got a message sying that I don't have the required DirectX version and when I tried to install the DirectX version provided on the NFSC dvd, it always ended up with a message about an internal system error :/ According to dxdiag I have DirectX 9.0c installed and fully functional, however, it is not the most recent build (I can't install the december one and I sure don't feel like reinstalling Windows
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The Win2000 compatibility method didn't work for me either, but I found another very simple solution and it worked like a charm
simply go to START->RUN and type in D:\AutoRun.exe -DXInstalled (where D: is the letter of your CD-ROM, so if you have several partitions or more drives, you might need to replace it with whatever letter stands for the drive from which you are running the NFS installation)
In my case after using that command I only got the "choose your language" screen and then it went straigth to choosing the installation directory and I had the game installed in no time. It didn't even display the EULA for DirectX, just skipped the whole DX crap and even though I don't have the latest DX build, the game is fully functional and I have no problems playing it. I hope this helps, at least it's worth a try, especially for people who can't get the Win2000 compatibility method to work
. Carbon worked fine but most wanted showed that i had no dx 9