'Failed to Find DirectX 9.0c' - Trying to Run Sims 2 on Bootcamp

Hello, hopefully someone out there will be able to help me with this. It seems to be quite a widespread problem as there are loads of threads like this, but none of the solutions offered seem to work for me. So, here goes: (I'll try to be as detailed as possible)

I am trying to run The Sims 2 on Bootcamp XP professional 32-bit on a 20GB partition of my iMac. I have an ATI,RadeonHD 2600 graphics card, which is apparently high enough to run the game. When however I try to launch Sims 2, I get this message:

Failed to find any DirectX 9.0c compatible graphics adapters in this system! Please make sure you have a direct X9.0c compatible graphics adapter and have installed the latest drivers provided by the manufacturer. The application will now terminate.

What do I do now?! If anyone could give me a helping hand, I'd be muchly grateful 🙂

Note: For some reason I cannot connect to the internet while on XP through wireless or ethanet. To get downloads across I have been putting them on a memory stick and transferring them from Mac to PC. I don't know if that will make a difference 😕

Note II: When I run dxdiag and click on the first (or second? Can't remember) tab, it says my version of DirectX is indeed version 9.0c. I have included a screenshot of this.

Note III: Dxdiag also says it is using the generic video driver, and that I should download the video driver provided by the hardware manufacturer. I have tried downloading something called the Radeon Catalyst which was linked to by someone else on another thread, but it made no difference. Any clues as to what to do here?