Ditto what Jonathan said, if you are going to shoot without flash his recommendations are the only way to do it properly. RAW + Higher ISO + Fast aperture lenses.
If you want to add light in the room by adding lamps/fixtures, try to stick with a consistent type of lighting. Mixing fluorescent, incandescent and halogen will give you color balancing difficulties. Fluorescent light also cycles (flickers very fast) so it can give strange balances shot to shot, I'd avoid it.
One final option is to use a shoe mounted flash and bounce the flash off the ceiling by pointing the flash head straight up. It gives a more natural appearance, with an even overhead lighting that fills up the room. This way you can also turn down the ISO, put the camera on Manual mode with a closed down aperture and faster shutter speed (ie. f/5.6 and 1/125) and then rely on the flash to light up the whole room. It gives you a lot of light, a lot of depth of field, and freezes motion.
Personally, I do both available light and bounced flash photography, depending on the "look" I'm going for.