This is pretty much worst case - shot at iso 800, underexposed by at least a stop (see bright pannel in the scene center). The noise is certainly visible but it's not enough to ruin the snap.

Camera:	Nikon D2x
Date:	Sunday, April 17th, 2005 at 10:35 AM
Exposure:	1/25 sec at f4.0
ISO:	800 asa
Lens:	12-24mm f4G ED DX AF-S Zoom-Nikkor at 12mm (equivalent field of view of a 18mm lens on a 35mm camera)
Photo Subject:	Eric, Gabi, Mark, Stephen
Photographer:	John Harvey
Larger Image:	2000 x 1331
Raw Image:	4296 x 2860