As far as I know, Virgin have ordered neither the 777 nor the Sonic Cruiser (yet). I can't really imagine them to be in a situation where they would order new planes. There have been rumours for quite a while that they'd go for the 777-300ER, but nothiing has been confirmed (to my knowledge). At some stage, there have been rumours that Boeing would take the A346s and deliver 777s later - which would give VS a bit of breathing space to allow the economy to recover. But that's all it is: rumours, with (IMO) little substance....
It is definitely known that they are negotiating to delay the A346 deliveries, though.