Apparently, AMD thinks that nobody uses Rage anymore, so they don't make any drivers for OS after Windows 98/ME. I know you can't get it, but you can try contacting AMD technicians here: http://emailcustomercare.amd.com/
Honestly I have no idea how you are running Windows 7 x64 on any computer with an Ati Rage II. There is no way the hardware that is running on supports 64bit. I'm surprised you are even runing XP on hardware that old. More like a Windows 95 box.
I had a Pentium 233Mhz with 48MB of RAM a 6.4GB hard drive and a Rage II+ back in 1996. I think I even got Windows 98 to run on it. Probably not 98 SE though.