If you want to utilize the 64-bit capabilities, the drivers he posted are your only choice. Although they came from ATI, they are beta, so be careful. If you decide you are going to go with 64-bit drivers, you should check your AGP chipset vendor, or your motherboard manufacturer, to see if they support it. If they already support it, you're fine.. you MIGHT have to download the drivers for your chipset manually since the 64-bit technology is semi-new. Then, install the ATI drivers. If you don't install the AGP drivers for your chipset, (assuming they aren't already installed) it will most likely give you some problems with D3D and OGL if you only install the drivers for your graphics card.
Make sure you un-install your ATI Control Panel FIRST--then install the software driver for your video card, and THEN re-install the Control Panel.