If you spent $300 on a card why didn't you do look into the product before shelling out the cash?
Sorry man, I just have no pity for people who have to get the latest and greatest without (from observation of the post) researching the product.
Download the latest drivers from ati.com, remove all software and hardware drivers from XP and reboot your machine. Then point the machine to the latest drivers for the hardware and install the multimedia software in the order that the documentation states.
If that doesn't work, send in a trouble ticket to ATI and take a hint that bragging rights on components for your pc will not get you chicks.