Depends on what you are looking for outta the newsgroup service - Retention (how long posts are kept), anoymonity, speed and cost.
there are premium (paid) newsgroup services ie Giganews, AstraWeb (my personal choice) and there are free newgroup services. Free services are generally slower, dont offer great retention.
Havent used any others besides Giganews and Astraweb.. thats why I gave ya's that link to Slyck's forums and guide.. only you can decide which paid service server you wanna go with.
All news groups servers basically carry software, music, movies newsgroups - the quality and amount tho depends on the service. Giganews is one of the larger older premiumn services thus has almost everything you could ask for.
