This how-to is as specific to Windows as you can get, which is not very specific, if you have another operating system, you probably know all about Python, and it's cross platform nature. (Also the best darned calculator you could ever want.)
SABnzbd+ (binary newsreader) -> http://www.sabnzbd.org/download/
Firefox (Browser) -> http://www.getfirefox.com/
nzbdStatus (Firefox plugin for Newzbin) -> http://sourceforge.net/projects/nzbdstatus/
Install SABnzbd+, following installation or by default, whenever you start SABnzbd+, your default web browser will open to http://localhost:8080/sabnzbd/
Fill out the server information by going to Config -> Servers, followed by going to Config -> Newzbin and filling out your username and password for Newzbin.
(Remember to 'Save Changes' after every addition or change to make sure it sticks.)
One more thing here, head to Config -> General and nearing the bottom on the left side, look for API Key: and copy the seemingly random numbers/letters.
Install Firefox and browse to grab the nzbdStatus plugin.
After installing nzbdStatus and restarting Firefox, you'll have an icon in the bottom right hand corner of Firefox, right clicking opens a task dialog box, click Configure nzbdStatus.
With the nzbdStatus Configuration box up, you'll need to paste the API key collected from the SABnzbd+ web panel, followed by pressing OK.
Head over to Newzbin and you'll notice the download NZB icons are replaced with a send to SAB icon.
SABnzbd+ will handle all the downloading of the NZB, downloading the articles linked in the NZB, parity checks and extractions.