You do not identify your needs adequately for anything approaching definative advice. In particular what sort of sport? Indoor or outdoor?.
For a general inexpensive walk around lens it is hard to beat the 18-135mm kit lens.
For a very superior walk around lens there is the 18-200 VR.
Either of these lenses would be good enough to stand alone. But neither is a good low light lens and for sport/action there is no substitute for good low light glass if you are shooting in indifferent light..
So approaching the "problem" from the other end there are 3 f/2.8 zooms in the 70-200 bracket:Sigma 70-200Nikon 70-200 VRNikon 80-200.
All are expensive and and heavy and the 70-200 VR will exceed your budget..
For indoor sport consider the Sigma 50-150 f/2.8. This lens is quite affordable..
All the above lenses would combine nicely with a Tamron or Sigma 18-50 f/2.8..
Personally I would go with the 18-135 and a used 80-200 f/2.8 (and a monopod) but the combinations are endless..
All the above lenses are reviewed here:http://www.photozone.de/8Reviews/index.htmland you can spend hours reading up on lenses from here:http://www.nikonlinks.com/equipment_lenses_general.htm.
*Nikon* D Eighty + Fifty - Other equipment in Profile.
The 18-135 or 18-200 VR are good recommendations - you could easily just go with one of those as a single-lens solution first..
You may also want to consider the very good 18-70, or even wait a bit for the promising 18-55 VR budget lens to come out..
For sports, it will depend on how challenging the lighting conditions are, and how fast the sport is. If you're shooting anywhere indoors or at night, you will need some sort of f2.8 lens - the Sigma 70-200 2.8, 50-150 2.8, or maybe a used 80-200 2.8 are good but pricey options..
If you're just shooting in daylight, and the sport isn't particularly fast (your kids just playing youth soccer, etc.), you can definitely get by with just about any budget telephoto zooms. There's a Tamron 70-300 f4-5.6 Di LD that's a great price under $200, and there's also an affordable Nikon 50-200 VR lens and a slightly longer and more expensive 70-300 VR lens..
My suggestion might be to just start out with the 18-135 or 18-200. From there, you can figure out what kind of range and speed you need for situations where you want a longer zoom...
Thanks to both posters..
The sports photography I am thinking of would be outdoor events, generally my kids. So golf, soccer, skiing, etc. I looks like the two lenses recommended might fit the bill. I'll take your kind recommendations as a good starting point for my research..
I can't speak for the D80, but from what I currently have and what's on my wish list I would go with the following (might slightly exceed your budget):.
Tamron 28-75 f2.8 (have this one, very sharp and good for low light, highly rated).
Nikon 70-300vr (highly rated, with very good reach, I have a Sigma 135-400 but if I had it to do over I would have opted for the 70-300vr as the Sigma is a little soft and without vr a tripod is needed in all but the brightest light)..
Nikon D50w/ Tamron 28-75 f2.8, Nikon 28-200 f3.5-5.6 and Sigma 135-400 f4.5-5.6Cannon S2isOlympus Stylus 720swGallery: http://etherialone.zenfolio.com/..
Thanks to both posters..
The sports photography I am thinking of would be outdoor events,generally my kids. So golf, soccer, skiing, etc. I looks like thetwo lenses recommended might fit the bill. I'll take your kind.
You'll generally need f/2 or faster for sports, though maybe not for kids and golf. So the 55-200VR or 70-300VR may be enough. But I'd be tempted to save up for a fast lens..
I'd also recommend the Nikon bargain lens for portraits, the 50mm f/1.8..
Have a look at the f1.8 50mm from Nikon..
It's very cheap, very fast, nice and light, very sharp and very very good..
Great for low light situations, great for portraits..
Bang for bucks, one of Nikons best..
Did I mention how cheap it was ?