Nikon d200 with a sensor size 23.6 x 15.8 mm and effective 10 Mp is not high above of 400D (almost equal features). That is matter of price ;o)
So all that determines features is sensor size and megapixels?
Here's an idea - try dropping a 400D and a D200 from various heights, in the rain, and see which stops working first.
As someone who doesn't use either system, I understand why people like Canon. I understand why people like Nikon. What I don't understand is why everything now has to be reduced to comparison between the two. Thanks to the internet (and before that the opinions of shop assistants) everyone is very aware that there's a big "Nikon vs Canon Debate", and that it matters. It doesn't. Either system offers more than you will probably ever need. I could say the same for other systems but that's a different matter.
Chavite, there's a significant price difference between a Rebel and a D200; I'm not sure why you're considering both. If a D200 is affordable to you, why not a 30D? But anyway, don't worry too much about comparing brands. Your stated requirement was:
"a quality camera that takes great shots". Any of Nikon, Canon or anyone else's dSLRs fit the bill there. More importantly,
"does either Brand take a better picture?" The answer is
NO. Canon's CMOS sensor is usually said to have better noise control at higher ISOs. Well my dSLR has the same Sony sensor used in Nikons, and images shot at ISO 3200 are for me completely useable. As you go up in price in either system, you generally find better sensors and more advanced image processing. Some cameras will have more advanced metering or autofocus than others... these may help
you to take a 'better' picture in terms of focus and exposure, but the camera won't automatically take a better shot.
IMO just narrow it down to camera and
lens combinations you can afford, and then compare them, in your hands, in a shop - ignore the spec comparison charts. Make a decision and buy.