[gchappel]

What are you going to use your camera/tool for?
I had a d70 and it was a fine camera. I started shooting the local highschool football team and other sports, so I needed a tool that shot and focused faster- so I purchased a d2h. Then a d2x for portrait work- the d2h files were too small. I have upgraded to both the d300 and d3- for different uses.
The d300 has a 1.5x sensor size- which you will find very useful for telephoto lens- it takes my 300mm and turns it into the equivalent of a 450mm. Great for sports and wildlife. The full size sensor has different advantages. First it has terrific low light capabilities- I have shot at an iso of 12,500! And they are useable. The full size sensor is also useful on the wide end. The 14mm remains 14mm, not a 21mm equivalent on the d300 or other 1.5x sensor.
Different tools for different jobs. Nikon, Canon, Sony, and a couple of others are all producing GREAT cameras- each camera has its strengths and weaknesses. It does get confusing- but I get more confused at the tool counter at Sears. Either of the new nikons is a huge upgrade from the d70. If you need fabulous low light capabilities jump on the d3, if not the d300 is a great all around camera. If your d70 is doing everything you need, spend your money on glass. Cameras are now like computers- new better ones will be coming out every year or so.
Gary