SABnzbd is a free tool that makes downloading files from usenet news groups a breeze. It takes the requested file information, downloads all the various parts, verifies all the parts are there, and puts the file back together for you.
"SABnzbd makes Usenet as simple and streamlined as possible by automating everything we can. All you have to do is add an .nzb. SABnzbd takes over from there, where it will be automatically downloaded, verified, repaired, extracted and filed away with zero human interaction."
To use SABnzbd, you will need access to a Usenet server and, ideally, a Usenet Newsgroup Search Index.
Here is the general outline of what you need to do to be able to download files from Usenet News Groups:
Get access to a Usenet Server (I recommend the Newshosting free trial $9.99/month special. Best price available and includes unlimited downloads, uncapped speed, and SSL)
Get access to a Usenet Search Index (these go up and down all the time so you'll need to search to find a current one - the programs listed below include built-in options for free searchers)
Download SABnzbd from sabnzbd.org
Configure SABnzbd to work with your Usenet Server (Configuration wizard helps you with set up)
You may also be interested in the following programs to automate your usenet downloading:
• Using Sick Beard (the ultimate PVR) to find and download shows... automatically when they are released
• Using Couch Potato to set up a "want to watch" list to find and download videos... automatically when they are released