I know the original poster wanted USB only, but I've got Nebula's PCI DigiTV Card. I had a Hauppauge WinTV-Go PCI card for analogue terrestrial (I'm sure you can get the PCI version for about £30 on the net), but when I moved to my student flat there was no space for a telly in my bedroom and I wanted digital.
The Nebula DigiTV an amazing card - I'm extremely impressed with it. Sounds like a cliché but it's one of the best purchases I've ever made. I thought it was a bit pricey at first, but now I don't mind - after all it's like buying a new TV. The software's good and they update it lots. The company is a small UK company and they're good for support if you need to phone them. I also got student discount - see the link on the bottom right of their homepage.
http://www.nebula-electronics.com/
They have a USB version of the DigiTV card on their website. Not tried it, but if it's as good as the PCI, then I fully recommend it. Another thing they're working on is a USB card reader to let you get Top Up TV in the future, if you so desire.
I've also only got it plugged into one of those set-top aerials as I've no TV point in my room. Works a treat. The
aerial I have is from Argos.
Plenty of reviews and advice are available at
http://www.tv-cards.com. (especially the forums).
Hope that helps a bit!
