A slightly shorter (and very much cheaper/lighter) alternative is the Sigma 50-150. For sports I've never found the VR to be of much use, except for panning stability.
I've shot both, extensively, and I'd go as far as to say that when your shuttertimes are short enough, the Sig actually gives you sharper, better pictures. But I'm quite a "shaky" person, so as soon as I get close to 1/f - shuttertimes, VR pays the bill.
I'd also say that F/2.8 is a must, not an "option" for indoor sports, unless you shoot D3-series or D700... Then you can get by with a 70-300VR quite alright.