Any experience with USB TV tuners?

I've seen a few on Ebay for <$50 and wondered if I could have a working TV window on my laptop outside of metro areas. Anyone have a working system for TV playable through their laptop? How well does it work? Is it worth the cost?
I dont have any personal experience with them, but I have had heard from other chasers that you need to make sure you are getting a USB 2.0 version and that your computer can handle the USB 2.0 format. The old school USB format (1.1?) is not fast enough to allow for full picture quality. Just something you might want to investigate first.

Its trivial with most computer nowadays but also make sure your computer can support a DirectX overlay too.
I have WinTV USB for my PC. The image and sound quality aren't the best, but then again I haven't compared this to any other tuners. The video lags a tiny bit behind the audio, but this is not often apparent. The WinTV is definitely watchable, and I use it all the time.

If you have a PC and want to do it right, I'd buy a video card that has a TV tuner built right in, such as the ATI All-In-Wonder cards.
Just going to use for chasing for local media updates so picture quality not an issue, but since plugging into laptop must be USB or PCMCIA. I have not seen if anyone makes a firewire version.
I had and used an ATI TV Wonder USB for a while and it wasn't to bad. Picture quality was pretty good as long as it wasn't full screen. The main drawback was the sound was only in mono. Easy plug and play was nice though.
I have Pinnacle Systems PCTV USB running on my laptop.

The pictures are acceptable quality. I have tried it with the laptop out in Lawrence, Kansas trying to receive on-air channels, it along with an external mount TV antenna does pretty good in receiving TV channels from about 50 miles away. It beats the expensive alternatives for TV's in the car.