What is the correct boot camp version to use with an early 2009 iMac 24 inch? Boot Camp assistant says software not currently available?

I have an early 2009 24 inch iMac. It is running mavericks. When I attempt to download using the boot camp assistant i get the message " software not currently available from server" So I went to the Boot Camp support website and there are about half a dozen versions of the boot camp download. None of them match my hardware. I tried the one closest, but when I went to run the setup in windows, it says my machine does not support x64. I have installed windows 7 home premium x64....It works, sort of. I cant get sound and my magic mouse behaves badly.

Do I need a different version of windows or is there a compatible version of boot camp for my system? Thanks for reading.