sorry, but your reply was more off than JIP's.
some company's do have others make their sensors (nikon uses sony sensors, for instance), but not all of them. canon makes their own sensors.
I think by 'compression software' you mean image processors, which are certainly not just 'compression' related. the image processor controls color, sharpness, contrast, noise, and image processing speed. this is obviously extremely important, and has nothing to do with wether or not you shoot RAW.
'those with the same resolution perform the same'.
that's utter craziness. does an off brand '
ebay only' 10 megapixel point and shoot have the same performance quality as a d200? of course not. and you hardly even mentioned sensor size, which has a huge difference in image quality and appearance.
lenses do matter a ton. I would venture to say that they still are more important in some situations than the body (most of the time this argument is like 'should i get the d200 and kit lens or a d70 and some nice glass? I wont be buying anything else in the next few years'). but the body is definitely important.