The boxes here are ridonculously fast and the only adverts we get is if we use the extra services like "catchup TV" and even then its a small box in the top corner of the tv while you can scroll through your selections below that.
Under normal use or even checking the TV guide we get 0 ads from the compnay themselevs, just the ads you get from the channel you are watching as that channel shows up as a small box at the top of the screen.
Just an example of the virgin media one:
http://theconnectedset.tv/wp-content/uploads/2010/12/virgin-media-tivo-tv-catch-up-m.jpg
In general adverts in the UK are looooot less than those in the states. Plus the service here is pretty cheap as well.
For £45 a month, I get a box that lets me watch one channel while recording 2 others, over 200 tv channels from around the world (including HD channels), unlimited calls to landlines in the UK, and 60Meg cable broadband. So I am wondering how microsoft will be able to compete really. Unless ofcourse they make a deal in such a way that the standard box from sky and virgin is an xbox..but that most probably will not happen.