It is not so much a "good" lens question.....if indoor school sports
is an interest of yours you will need a fast lens.....and as of today
there is not one that will auto focus on either the D40 or the D40
X...but you would think that there will be a couple available
soon.....both of the 40s are very good cameras.....if the lens choice
was soon addressed.
The best lens available now is a used AF-s 80 to 200 F2.8 and its
about 900 dollars used......and of course the 70 to 200 VR. $1600.00
new. If you have a while before you need the sport lens.....I am
pretty sure there will be less expensive options soon.