Comparison of .dbf files using Python

Background- I am working with a .dbf file that is updated nightly on an internet site and I work with daily. Rather than working with a whole new file each time (I want to keep my own updates on my existing .dbf file) I want a tool that will find those new enteries and create a new .dbf file. Information- I need a python script to compare an existing file that will be located on the internet with a file that is located on my computer. Taking those two files that have been compared-create a new file that has all the differences between the two .dbf files in the same format has the other two .dbf files. I'm new at this project stuff, but more information will be provided and I want to be involved in the process of making this python script. Frequent contact by email (I use gmail) is a must.