EasyAcreage is program for WinXP or Vista program that allows you to calculate area from KML files exported out of Google Earth.
This means you do not even have to leave your house to measure a field anymore. Simply use the free version of Google Earth, mark the area you wish to measure, save it as a KML file and drag and drop it onto EasyAcreage. Voila!
It is important to note that by using EasyAcreage, you do not need Google Earth Professional to measure area. Using EasyAcreage you can use the KML export methods that exists in the standard free version of Google Earth and get the same results at a fraction of the cost.