This is one of the better primers that I have come across regarding how to understand the basics of digital filtering. I wanted to pass it on to anyone else who might be interested. It helped me have a light bulb moment or two, so maybe it will help you as well.
The full title is "The Audio Engineer’s Approach to Understanding Digital Filters (For the idiot such as myself)"
by Nika Aldrich
link
http://www.users.qwest.net/~volt42/c...ng/Filters.pdf