Hi,
I work as a part-time freelance photographer for a local newspaper and have just recently upgraded to a Canon D30. Althought it has only been a short time I can honestly say that this camera is going to make a huge difference to my work.
I have not used the Nikon and can only refer to the Canon, but basically I cannot fault the images. When I first used it though I was shocked at the the preview, I really thought that there was something wrong with my lens or my technique. I couldn't have been further from the truth. When I eventually got the images home and used PS 5.5 and got the unsharp mask working I nearly fell off my seat. The images practically jumped out at me.
I have shot some local sport using this camera and found it to be adequate for the job, however a little slow on the focussing side. However, I have since set my camera with one of the custom functions to lock the focus at the touch of the * button. I will be keen to see how this operates in action shots. The results I did get however were very clear and sharp and I was delighted with them. I even had to shoot at 1600 iso at one point because the light was so poor, I was well pleased with them even though they were noisy - but acceptable.
If you can afford the Nikon with nikon lenses then you are very lucky, but I doubt your images will be significantly better to justify the extra. If I had that kind of money I would have the D30 kitted out with everything. Beleive me, you will get your money back in no time with the Canon - you will not regret it.
Paul Murphy.