I never, ever, ever use dollies to move games up and down stairs. The dollies just bounce the games around, and the furniture dollies might be smooth, but it is still essentially just sliding the sucker down the steps at that point. If I am doing that I might as well just slide the game down the steps on it's back, less likely go get away from me that way.
My normal method of doing stairs is to pull the monitor from the cabinet, move the monitor down the stairs, and then get someone else to help me with the cabinet. They are a lot lighter without the monitor, and thus much easier to move (unless it is an atari cabinet, in which case it is going to be heavy and have no place to grab no matter how you do it).
I have also (on a few occasions) SOMEHOW managed to move an entire game into or out of my second floor apartment by myself with no assistance. I can only do it with plywood cabs though, and I have to take all the weight out of them first. A bare plywood cab is way under 100 lbs, and can be handled by one guy, it is just awkward.