The ATI Rage Fury Pro is an obsolete graphics card. It only supports up to DirectX 7. Halo requires a graphics card that has DirectX 9. You cannot play the game unless you replace the graphics card. Since the card is from 1999 I can only assume you PC is just as dated.
While you may be able to replace the graphics card, it is best to simply buy a new PC. A relatively inexpensive modern desktop or laptop will be able to play Halo since integrated graphics have come along way in the past several years. If you are going to buy a desktop or laptop, do not simply buy it. Post a link to it so people can see it and determine if it is a good deal or not. Desktops are generally better because they allow you to upgrade more than just RAM and the hard drive. But laptops are compact and portable.