iMac 20" Intel - Win7 Install Does Not Support Bootcamp 64-bit? [duplicate]

iMac 20" Intel - Win7 Install Does Not Support Bootcamp 64-bit? [duplicate]

I have a 20"Intel iMac running OSX Leopard. The computer was dual booted using bootcamp to run win xp 32-bit. I have just erased this partition and installed Windows 7 Ultimate 64-bit. When I insert my leopard disk to install bootcamp drivers it fails with the error message: