Agent is available in both paid-license and freeware-license versions. Actually, it is the same program — the difference is whether you have purchased a license key or not. If you don’t want to purchase a license, Agent will revert to the freeware version after 30 days.
If you are running Windows, you already have one program that can do Usenet — Outlook Express. Start Outlook Express, then from the menu, pick Tools, Accounts… Select the “News” tab and fill in your ISP’s news server (Cox’s news servers have names like news.east.cox.net, news.central.cox.net and news.west.cox.net; – your ISP probably has a similar naming system.)
If you use Mozilla Thunderbird or Opera, you can use them to read news. They have similar configuration systems to that of Outlook Express. Outlook, on the other hand, does not do Usenet news — it hands that task off to Outlook Express.
If you are in the Linux world, you have many, many more options.
And, finally, you can always use Google Groups to read Usenet. Google Groups is not Usenet, but it includes ways to read, post and, more importantly, easily search Usenet for information.
For a real Usenet service, with many more newsgroups than most ISP’s carry (those that still offer Usenet newsgroups), I use Giganews. I’ve been using Giganews for several years and am impressed by it’s speed and the retention time of posts, too. For those who frequent the alt.binary newsgroups, it’s got those, too, also with long retentions. Giganews offers a free trial, too.