Did they allow you to download it free?
I was able to download it for free. I connected my Vista HCx and did an update on the Garmin web site. It took me a few tries to download the file, it's about 2gb.
I have the NT version, I don't know if this is compatible with the 60CS but the map sizes would fit on the 52mb depending on how much area you need. North Dakota is 6.3MB, Chicago is 13MB, Iowa is 13MB, New Mexico is 10.9MB; you should fit a couple of states on there.