If i wanted to run a usenet feed on one of my servers for some users - how would I go about hooking it up?

I guess both on the business side, would I pay somewhere to get it on the feed or ? Hosting with ServerMatrix, not sure if there are any possibilities there?

On the technical side, I'd like to set up access only for those with a valid account - I dont need to do accounting etc, just simple authentication (I only have a few customers that would need / get this).

You may want to look into reselling for one of the many usenet providers out there, your customers will go to those servers not yours. Try www.supernews.com and others, like I say there are more and you could probably find some comparisons if you look.

If you realy do want a news feed, you can get one from here newsfeeds.com/ihave.htm but it will get expensive real fast. A full feed will consume 10-20 GB/day of traffic, and costs $500/month, so reselling an existing service is
probably the best way to go.