iirc, Virgin only 'lease' their boxes to customers, thus you do not actually own it to sell (hence they repair/replace them if they have a problem, unlike Sky where you own the box, and are responsible when they go tits up out of warranty).
So essentially, if you sell a Virgin Media/NTL/Telewest branded box, you are actually selling stolen goods?
Matt 100% correct all virgin media boxes remain the property of virgin media and to sell them on is fraud. They will only ever work when paired with the original smartcard whilst a subscription is being paid for so buying a virgin box without smartcard will not work ever