ORIGINAL: npaden
I think you can do what you are talking about in Google Earth. At least I think you can because I've been doing it.
This is the free version, not the one you have to pay for.
The benefit to doing it inside of Google Earth vs. doing it using a still image and the microsoft paint program is that you can zoom in on different areas and the shapes and markings zoom with you.
I think you have to have the pay version to be able to calculate acreage with Google Earth but I use the USDA software to calculate the acreages and then just type those into Google Earth.
Can you transfer the tracks and GPS points to your GPS?