I have that lens (70-200mm f/4) and it's fantastic. Sharp, sharp, sharp! Of course, I'd love to get the f/2.8 IS version, but it's twice as expensive, plus a lot heavier.

That said, for indoor sports you would have to hope for either a really well lit place, bump the ISO up to at least 800 and/or use flash for f/4 to be fast enough at 200mm.