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

Can you provide some info on the types of indoor kid photos you're talking about?  Are we talking organized sports or plays or photos in the house?  The reason is - there is no single answer for everything.

For example - if you want to shoot sports you need fast focus, wide aperture lens AND a lens the proper focal length for the sport and your distance to the action.

If you're talking family shots, that's a bit different situation.  The problem there is - houses are darker than gyms so you can have situations where fast primes and high ISOs still aren't good enough.  Additionally - when you want MULTIPLE kids in focus, using wide apertures doesn't work well.  In that situation a bounced external flash yields better results in my experience.

For example, here's a sports shot - relying on wide aperture and high ISO

But in this shot - siblings playing around the above solution wouldn't work well - not enough DOF and not enough ambient light for high ISOs to work well.  So an external flash produces better results:

So - to give you the best advice it would help to know which situation(s) you're talking about because no single solution will work well in all environments