I've written up a guide that assumes next to nothing about windows command prompts.
The Overviewer is a command-line program, and that is a barrier for a lot of people. While we have to compromise at some level -- not all the documentation can be written assuming no command line experience -- we do want to lower that barrier.
So with that, I present the first draft of the Windows Noob Guide to The Overviewer. Hopefully that will be enough to get more people started.
We love feedback. Please join us on IRC and help us improve the documentation!
About a GUI: We would love to make a GUI frontend for The Overviewer, but nobody has put forth the time and effort yet. Several people have started a GUI in the past, but nothing has materialized. If you are interested in helping us out on this front, please join us in IRC and discuss your ideas.