Okay, this is making sense to me - thanks.
Yeah, there are a couple extensions that are executable - .bat, .scr, .com, and .exe are the main ones, so you have to be careful to screen out *.jpg.scr or *.mpg.bat type files; generally anything with a double extension is bad. Just be careful to only download files with extensions you reconize, like .jpg or .png for pictures, or .mpg/.avi for movie files.
Lest anyone get the wrong idea about spam and virii on Usenet, it’s a text medium. When you open your newsreader and download the headers for any newsgroup, you’ll get a refreshed listing of hundreds or thousands of files posted to that group. You’ll be able to see what the name of each one is. You can’t click on one and open it from the browser, you have to download it first. So when it’s physically on your computer, you can check the file extension. If it’s something other than .jpg or .avi or .mov or .mpg/mpeg, don’t open it.
Of course, people send in fake files with virii attached, every day, all day, to all the porn groups (unless any of them are moderated). Generally, the smaller the line count of the message, the more likely it is to have a virus attached. But even if you click on a header and look at the message in your browser, you won’t get any virii if you don’t donwload the attachments and open them.
What you need is a newsreader.
Mozilla has a passable one. I use Agent ($20).
Find your ISP’s newsserver. If it’s decent it will have one. If you’re at work, you may have to use Giganews or something like it.
Discussions like this make me feel old.