Sigma 17-50mm f/2.8 EX DC OS or Nikkor 17-55mm f/2.8G ED-IF

Wondering the same thing myself.  Looking to potentially buy a 17-50 f/2.8 lens as well.

In my mind, I'm rating the lens as follows:

Nikon - Better build quality, probably better optics

Sigma - OS(VR) !!!

Not sure how I can buy a lens such as this without OS/VR/VC etc.  Sure it's a f/2.8, but indoors, at night time, even at f/2.8, shutter speeds are still going to be slow enough that the OS/VR/VC seems like a must to me.

If that is the case, then the Sigma becomes the obvious choice.

Additional thoughts?