Windows 7 with late 2009 27 inch running Mountain Lion

When I load Mountain Lion onto a late 2009 iMac 27inch, and then use Bootcamp to install Windows 7 64-bit OS, which drivers do I use? The ones on Snow Leopard (when I had that) didn't work for a reinstall following the repartiion instructions, neither did the Lion option.

I had Windows 7 with 64-bit OS install on this computer using Snow Leopard for 2 years before a virus required me to wipe that partition and start over.

Also, if I do have the right drivers, when the computer restarts after installation, do I use the install disc or let the ocmputer take over?

Finally, if I have tried this in Lion and now have Mountai