There is no comparison between Sky and Virgin. After years of being a VM customer I switched at the end of last year and went to sky. Not being able to play games due to jitter and overs-subscription once again was the last straw, along with the time from reporting to the fix date being a year.
Sky Unlimited on the other hand seem to have been pro-active on upgrades and made my already working broadband even better. They just add more bandwidth compare the VM who tend to impose more restrictions and traffic management on its users.
Ultimately it all boils down to investment and the fibre standards used for the broadband products, and VM are pretty much bottom of the pile.
MySky
http://www.thinkbroadband.com/ping/share-thumb/5547f...