However, if you have a digital TV (or an analog set with a digital-TV converter), you already have a DTV tuner--whether you're using it or not. On a typical , the tuner input is the one that's labeled 'TV' and connects to an antenna or cable the same way the Boxee does, via a coaxial input. (Of course, pay cable services also deliver over-the-air stations, but the point of the Boxee tuner is to fill in the blanks that you'd have without the pay service.)

What the tuner brings to the party is integration of over-the-air broadcast channels with Boxee's software and features. If you own a Boxee and use your HDTV set's own tuner, you get the same stations, but you have to switch inputs between whatever the Boxee is connected to (for content you stream from the Internet and your home network) and the TV tuner, which also involves fiddling with multiple remotes. On top of that, you can't share your live-TV habits with Facebook friends or use Boxee's electronic program guide (which usually provides some program info you don't get over the air). Another benefit of the Boxee tuner: With some programming, you get easier access to related Boxee content (for example, other series episodes). In other words, paying the $49 cost of the Boxee tuner to enable the Boxee Live TV service buys a measure of convenience--if you're committed to Boxee as your primary TV source.

Setup is fairly straightforward. The Boxee Live TV tuner is a USB dongle about the size of a typical cell phone modem or Wi-Fi adapter; it plugs into one of the two available USB ports on a . When you fire up the Boxee after connecting the tuner, with the antenna or cable also attached, on-screen prompts direct you to get a software update that adds Boxee Live to the menu options. The first time you run Boxee Live, it performs a channel scan (much as any TV does during setup if you're using its tuner) based on your input of your zip code and whether you're connecting to an antenna or a cable. This process typically takes 5 to 10 minutes or so.

If you're using an external antenna, whether your own or the one that Boxee ships with the tuner, the number of channels you receive will depend a lot on both the location of your home and the situation of your antenna. You can't do much about the former--if you live in an area with poor reception, you may never be able to get some stations--but you can take steps to improve antenna placement.

If your set is situated indoors and far away from a window, don't expect to get much live TV unless you invest in a long cable that will let you put the antenna outdoors or at least next to a window. (This problem would be evident whether you used the set's tuner or the Boxee tuner.) In my tests with a TV located some 40 feet from a window, the Boxee tuner and its included short antenna could pick up only a half-dozen or so channels; when I connected the antenna to a 50-foot coaxial cable and placed it next to a window, though, a new channel scan found 53 channels. Quality in some cases was uneven: Stations with weaker signals sometimes disappeared completely.