Make sure you have up-to-date and compatible device drivers for your soundcard, motherboard and especially your video card.

Seeing as you have an AMD setup, I suggest you go here if you have a VIA chipset motherboard http://www.via.com.tw and download the latest 4-in-1 Hyperion driverset for your OS.

Then go to http://www.nvidia.com/content/drivers/drivers.asp for the latest/BETA Detenator drivers.

Ensure you you also have DirectX9.0c installed aswell, as I have a feeling thats what RTW was released with...