Guys the Sigma 24-70 is brilliant - I chose it above the nikkor lens when I bought mine. Because in my own tests in the car park I couldn't tell the difference - this is the new Sigma. The old 24-70 wasn't half as good. It is a big lens, heavy - but unless you are a 60 pound weakling you should manage - go read the popular photography review if you don't believe me.

Do yourself a favour and rid yourself of the 3rd party myth, it's just marketing. Obviously many cases the manufacturers are better but often not. I played with a Tokina 16-28 today. In no time my nikkor wide angle will be on the classifieds - its in perfect condition but the Tokina even at the same price as the better nikkor than mine kicks arse - at half the price - no brainer.

Sorry to come across so strong. If I had the same decision again I would take the Sigma 24-70 f2.8 - it's very very difficult to fault.