the equivalent crop lens is the 17-55mm 2.8 nikon which is good, but for crop sensors.
They are both good lenses, I have used both but the 24-70 is an expensive piece of glass. If you are planning to move to FF then get it, all you need is that and the 70-200VR to cover most of the photos you'll ever take. If you need wide, you can get a 17-35mm 2.8 but that's pricey too.
If money is tight you could consider the sigma 24-70 2.8 which is also a FF lens and I have that one. Bit softer when at wide apertures but at less than half the price you can't complain.