I've been having this issue too, same area and same BQM results basically. Great down/up speeds but god awful packet loss causing online games to be unplayable for 2 weeks.
I've been on the phone the last few days /w virgin and was told there is definitely a network problem in our area and its scheduled for repair next Monday. If it solves the problem or not remains to be seen but at least they are aware of an issue in the line. Hope this helps somewhat since it sounds like you aren't getting very far yourself.