Virgin broadband can come down via cable (as was provided by NTL or Telewest), or via a phone line.
What you get depends where you live in the country.
I have it via cable (I was a Telewest customer) and pay �25 a month for a fast download.
Generally the service is fast and reliable.
I have noticed in the last few months (since Virgin merged with NTL/Telewest) that the speed on some evenings can get very slow, but overall it is pretty good.
Of course via phone line may be very different.