Not a "Must Have" really, though I wont give it up. Its a great tool to have in your toolbox, no more, no less.
In your specific
conditions, taking pictures of people in the availible dark still requires a fast shutter
to stop thier
motion. Think fast prime lenses* and high iso settings. In general snapshooting, A/S is great because you'll rarely get blurred picture from camera shake unless conditions are WAY unusual.
For A/S your looking at Sony which might
compromise on noise, or pentax. Although you could still buy a used minolta (out of production). Canon and Nikon offer stabilzed lenses (mostly telephoto) at a premium price, not as economical but still a good solution if it fits your budget.
*By fast prime lenses, I mean specifically a 35mm or 50mm f/1.4 or f/2. The 50mm is better for head and shoulders type shots because otherwise you need to get back kinda far, so I'd concentrate on what a 35mm will do to your budget if you want good no-flash indoor pictures.
Here is my newest favorite example of why I shoot a stabilized 6mp SLR:
Minolta 7D 1/20s f/5.6 at 17.0mm iso800 (Though I took some longer exposures too, and they came out sharp because of the A/S)