Matt Laur , Dec 14, 2007; 08:02 p.m.
John: I'm sure you'll get a lot of this, but... faster lens! If you can go to f/2.8, you're WAY ahead on the need for such a high ISO, or on the noise you should expect to tolerate. If you're OK, results-wise, with 1600 speed film and a 4.5-5.6 max aperture, then you'll REALLY be OK with ISO 800 and a f/2.8 lens. My Nikon D200 is quite tolerable at 800, and such noise as does appear there is easily dealt with in post-production.
The new D300 (and VERY clean at 1600) is outside of your budget, but the D80 should behave quite nicely. And, with an APS-C sized cropped sensor, you should be OK with a lens that only hits 200mm on the long end. Still, you're in for more than $1000 to do it in a tolerable way... but it doesn't have to be a new D3 to very nicely handle your requirements, given your existing threshold of noise pain.