Thommo,
Don't count too much on the stage lighting to help you out. It's quite likely to be cast in one colour or another, and the D70 seems to be overly sensitive to red, meaning that if you're stuck with red lighting and available light, you're going to be looking at some serious issues.
Remember too that a stage is an area of high contrasts. Your lead singer will be well lit, but his or her immediate surrounds will have no lighting at all; if you're bumping into high ISO settings, those dark areas will be even more noisy than the band while they're trying to tune up.
While the lead singer will be highly illuminated, you'll also get to make the following observations: the greatest ego will be with te lead guitarist, and he'll be wanting all of that light himself. The rhythm guitarist, and also the bassists, won't be as egotistical, and may even not stand within any available light source. The drummer of course will be on a riser, but several feet further back, and again, mostly out of direct light. (That lily-white skin is his drummer's suntan, acquired through many painstaking years of arduous sleeping in till 2 pm every day.
Speaking more seriously, I will generally shoot with either the built-in flash or the SB800. Manual
mode, 1/30 - 1/125 sec @ f5.6 - f8. At least one stop down from wide open; two stops are better. Dial the FEC back to between 1.3 - 1.7 stops. That's enough to give you an adequate level of fill for the shadows left by the stagelighting, but still permits the stage lighting to remain dominant.
Lens choice - I like to get up close and personal, and the 24-120 is ideal, especially if you can work at the foot of (or to one side of, but on) the stage. The kit lens doesn't have the same reach, but is fine and works well. Note my comments regarding aperture above.
Use the camera with the lens at its widest setting; don't put it anywhere near your eye, but hold it towards (and in the direction of) the musos. Or use it at max zoom, shooting from eye-level, and focussing on the eyes.
If you're shooting the whole band, remember that you're going to be dealing with light fall-off issues between the front and back of the stage.
Here's a few images I've shot. Back up from there to see a few other dates at the same venue as well. Lenses vary from kit, 50 1.4, 24-120, and even a couple using the 80-400, mostly ISO 200 with a bit of flash.
Play with your settings, shoot raw to give yourself maximum flexibility, and have a ball.
And don't forget to listen to the music!