My computer doesn't recognize sound card or video card?

I reinstalled Windows XP to my another computer and now it wont recognize the video card or sound card. I know that the video card is ATI but i dont know the model. Please i need help !|||Download Everest. Its free and will tell you what your devices are. Then, you can install the correct drivers.|||go to http://www.innovative-sol.com/drivermax/ and download drivermax. It's free and it will find all the newest drivers for you..