For less than $100, you can feast your eyes on local, over-the-air HD channels; all you need is a laptop/desktop with some decent horsepower under the hood.

The secret? A USB HDTV tuner, of which there are literally dozens available. Most of the USB HDTV tuners I've seen look like typical USB memory sticks, and they usually come with compact antennas that you can attach to a wall or outside a window.

The beauty of USB HDTV tuners is that they can grab free, over-the-air HD signals from local TV stations—and with the right software (and plenty of free hard drive space), you can even record full-on 1080i/720p programming. Some USB HDTV tuners will also decode unencrypted QAM signals over cable.

Setup is usually a piece of cake. Typically, you install any bundled software, plug the tuner stick into your laptop's USB port, and position the included antenna for the best signal—outside is naturally the best, although I've had good luck using antennas in my office cubicle (which, I should note, is reasonably close to a window). Want to see which over-the-air HD stations are in range? Plug your address into AntennaWeb.org to find out.

Price is, of course, one of the most appealing features of USB HDTV tuners. Most hover in the $80-$100 range, although plenty are available for $50 or less. There's also a $15 (after a $20 rebate) tuner from KWorld that's been getting some attention.

What's the catch? Well, HDTV performance over your laptop will only be as good as your system's processor and memory will allow. For example, Pinnacle recommends at least a 2.4GHz Pentium 4 or 1.7GHz Pentium M plus about 1GB of RAM for HDTV viewing—anything less, and your HD stream will slow to a crawl.

My picks? I reviewed Plextor's PX-HDTV500U last year ($99, less online) and was pretty happy with it, although it lacks a QAM tuner. Name brands such as Happauge, Avermedia, and Pinnacle also make USB HDTV tuners, and of course, there's that bargain-basement KWorld tuner. (Check out the selection at Yahoo! Tech and Yahoo! Shopping.)

When you're shopping, keep an eye out for USB HDTV tuners that bundle software DVRs, which work (more or less) like your cable box at home. Keep in mind, however, that you'll need a monster hard drive if you intend on saving many HD shows; in my tests with the Plextor tuner, just five minutes of HD ate up more than 250MB of space.

Have any USB HDTV tuner recommendations or tips? Fire away.