Most servers don't have viruses ... In the two or so years I've been using it, my anti-virus has only detected three viruses from the servers, about a dozen within downloaded files (I always scan the files after I dl them) ...
What news servers ?
How beneficial it will be to you depends on your news server...if you use the free one offered by your ISP, it may not even be worth your time depending on the bandwith limit and the retention rate. Thats where places like http://www.giganews.com come into place....it seems kind of ludicrous to pay for it, but when you see how ridiculously fast the speeds are and the massive amounts of data you can download, it's worth it. The first time I used newsgroups, I downloaded around 7GB my first day.