First, I agree with the plug for B&H Photo. I've bought lots of gear from them. If they say it's in stock, they mean it and you'll get it right away. There's always somebody with the camera for less money, but never a whole lot less.

Honestly, both Nikon or Canon will make you happy. In terms of night photography, I can't speak for Canon, but here's what a D70 can do. I took this picture on July 4. These are some locals who like to blow things to bits. This guy is wearing a custom metal hat, loaded with all manner of fireworks. He's dancing around while the fireworks are shooting out of his head. (The hat has a WW1-era helmet welded into it for safety, and he's also wearing earplugs and welder's leathers.)

I was about two meters away, laying on the ground and shooting as fast as I possibly could, despite the occasional embers falling on me. They didn't give me a chance to run back to my car to grab my tripod ("we're doing this now, you ready?"), so this is hand-held at 1/30 second (using the kit lens, wide open), bracing my forearm between the ground and the camera.

The camera, in its own auto-ISO wisdom, decided to expose the image at ISO 640, which turned out to be a bit underexposed for the background foliage, and a bit bright for the fireworks -- probably the right compromise. Luckily, I always shoot raw, so I had plenty to work with. First, here's a draft of the image, color corrected and cranked up to 3200ASA or so using Adobe Photoshop CS:



At 3200 ASA (not even officially supported by the camera but easy to do after the fact), the blue channel is pretty much useless noise in the dark bits, but there's still good signal in the highlights. I redeveloped the image at a lower speed but imported the full 16-bit data into Photoshop, where I then played lots of games with layers, channel mixers, and masks so I could work separately on the dark parts and the bright parts. Here's the result:



In short, it took maybe ten minutes of work, but the end result was better than I could have ever expected. So, I ain't saying Nikon is better or worse than Canon. I'm saying that either camera could have taken this image, but to really perfect it, you've got to work it afterward. Sure, there's some noise (one-to-one pixels of the final image below), but it's quite acceptable, all things considered. The only question is whether the camera can correctly pick good exposure and focus settings, since you're potentially far too busy to worry about those things.