I it possible to limit her bandwidth if your router has the settings to do so.
Which router do you have?
I have the DGL-4500 and i can control the entire network as to who can access what on the internet to bandwidth throttling. And Game Fuel is awesome. Anytime my computer wants to hog the bandwidth it can and drop everyone else down to dial up speed..

If you limit her connection to 500k then she will still get good streaming. Leaving you the rest of the bandwidth to enjoy for yourself.