[Neithan]

The Balrog would definately be able to use it. It would seek to overthrow Sauron, but whether it could accomplish this is another story. It could pobably bring all of the Orcs of Moria under its contol pretty quickly and that would give it the beginings of an army. I don't think the Balrog would be able to overcome Sauron's will that was put into the Ring so it would still want to serve Sauron rather than the Balrog. For the same reason the Nine would be divided in their service and would probably not fight against either of them. Even if the Balrog did manage to defeat Sauron (and that would not be easy, even with the Ring) it would not be able to permanently destroy Sauron's body. Sauron's power would remain in the Ring because the Balrog would not be powerful enough to completely master it and so he would keep coming back. The scary thought is that the Balrog would gain access into the minds of Gandalf, Galadriel, and Elrond. I don't know if he would be able to master Gandalf, Gandalf had the greater mind but that might not matter when the Balrog had the One Ring. My guess is that he would master Gandalf.