if you switch to virgin, what you may end up with, if things ever go wrong, is a customer care department that doesn't, well, care.
last year I had nearly 6 months of an intermittent service. Virgin knew there was a problem and even knew what it was and how to fix it; thing was, they couldn't be bothered. Now the same thing is happening again - the service was off over the weekend and has been intermittent ever since, and I'm told "it'll be fixed next month. unacceptable!