Ops... It was not my intention. When a answered "yes" for the question "Nobady has this question?" (or some question like that) I thought that I was saying "Yes, I have searched in this forum and I'm sure my doubt is new". Sorry for my mistake, but it's my first post here. Do you know how can I change it for getting more attention?
Dan, about my original problem, my study area is in Brazil. Actually, it's two administrative regions of São Paulo state. So, I think the coordinate system "SR-ORG:7823: Albers Conical Equal Area Brazil (SIRGAS 2000)" that you listed will be appropriated. However, I couldn't find it in the XY Coordinate System of ArcGIS (please, see the picture attached). A lat/long (geographic) coordinate system, like those in the picture you attached, will not be useful for me.
Thanks for you attention, Dan.
Sincerely,
Pasqualotto.