M. Hayward , Mar 05, 2007; 08:51 a.m.
I doubt you can use a speedlight with indoor sports. Buy a 50mm f/1.8 Nikon lens for $100 or so, use aperture priority mode, set the aperture to f/1.8 and set the ISO to 800. Neither lens you have will get the job done indoors without flash.
Outdoors, use the 70-300 on program with ISO 200 or 400 and you'll get good shots.