Thunderbird Review
Thunderbird is a mail reader and Usenet client that, like Firefox, is free. While it really is not meant to be used for downloading binary files off of Usenet nonetheless it is very good Usenet client ( and email client ).
Here is a picture of Thunderbird in action here.

Pricing
Thunderbird is FREE!
Usenet Search
Thunderbird does not do Usenet search but you can’t beat the price.
NZB Support
No NZB support, Thunderbird is meant for reading Usenet and not binary downloading.
Platform Information
Thunderbird, like Firefox, is available for Windows, Mac and Linux
Conclusion
If you want to read Usenet newsgroups and don’t want to pay for a newsreader and do not want to download binaries. Thunderbird is for you.
More Details
Despite being free and a decent Usenet client Thunderbird can be difficult to configure initially for Usenet service like Giganews and Astraweb where you have pay for Usenet access.
Thunderbird Usenet Configuration Tips
Install Thunderbird as normal and add an NNTP/Usenet connection. Next, to get Thunderbird to accept your username and password you will need to click on the manage newsgroup subscriptions link.

Next choose your username (be sure to click save !! )
Choose your Password ( be sure to click save !! )

And then watch as Thunderbird connects and downloads all the available groups.
See above Newsgroups are downloading .. ALL is working just fine.
Some of the advantages of Thunderbird is that it is FREE and that is easy enough to use (once you get past the initial configuration ). Thunderbird has SSL encryption support also.
