I've talked to and met a number of people recently that are just getting started in real estate photography. Many of their questions center around what equipment and software do you need to get started. Here is my current recommendation assuming that you want to spend as little as possible:
When you have extra budget spend it on the glass because that's something you will keep for a long time and in real estate photography the wide-angle lens is the most important piece of equipment you own.For flashes I recommend getting the top of the line (most power) and the same brand as the body you buy because this will be the flash you use on-camera and you will have the option to use in either manual or automatic mode. As you purchase more than the first flash purchase SB-26, SB-80s since they have optical triggers.For photo-editing Lightroom is far and away the easiest to use and best choice but you will need something in addition to Lightroom to straighten verticals and remove barrel distortion. There are others but PSE 6.0 is a very good choice.Unless you spring for the more expensive glass I recommend above, all of this adds up to around $1650 whether you purchase Canon or Nikon. I think this list is a rock bottom that you will need to get into real estate photography. Don't try to do it with a point an shoot camera. $1650 is a pretty small equipment investment to get started in a business.