Best DSLR + lens combo for low light, indoor kid shots

Because subjects in low light are some of the most demanding for photography you can spend a fortune (pro camera, fast zoom lens) and still not get the best results; the biggest difference is going to be technique. And once you get the technique that's still not enough because you'll need to compose well so the shot says something. So whatever you buy I would suggest practicing a lot and don't expect the camera and lens combination to do the heavy lifting - that's up to you. You may also want to practice without your kids lest they get tired of being targeted for trial runs...

One exercise could be to stage a shot, so you position the camera (facing a window - not!) and get all your camera parameters in order before your subject crosses (goes for a glass of water to the kitchen or something) and can get the shot. Some interiors are so dark the only way to get the shot will be with a flash or several flashes (hint: not the one on your camera).

I would get something like a Canon T3i or 60D and the 85mm 1.8, so you're not in their face, or equivalent fast aperture lens and camera combination in other brands. Good luck!