I'm looking for an every-day walking around zoom lens for under $1000. I've seen mixed reviews (and heated debates!) around here about the Nikon 18-200mm VR. The VR sounds nice, but I'm concerned that the speed is the same as my kit lens (I have a Nikon D40 with the 18-55, so I am limited to AF-S lenses, or HSM from Sigma). Sigma has a 50-150mm f/2.8 lens that looks nice, and is slightly more expensive than the Nikon 18-200mm. Has anyone tried this lens and have any opinions on it? I don't think I would miss the massive 18-200 range of the Nikon. I already have a Sigma 10-20 for wide angle, which I'm happy with, so I think these 2 Sigma lenses will cover any situation. I want to be able to shoot moving subjects in low light (kids running around, rock bands performing, etc), and also portrait photography down the line. I will upgrade my camera body in the next couple of years, so I am willing to buy decent glass now. So what do you think of these 2 lenses, and are there others I should look at? Here's the Sigma 50-150 at Anazon: http://www.amazon.com/Sigma-50-150mm-Telephoto-Digital-Cameras/dp/B000HPOQKS Thanks!