The D50 was a lower-level Nikon body than was the D70..BUT, the D50 produced a bit "punchier" more directly-ready images than the D70 tended to...D50 images were more eye-candy-like than D70 images at the default parameters.
The D40 was also more "punchy", and more "modern"; I own a D70,still...I occasionally use it for hazardous duty...it is kind of the "old-school" Nikon...before the in-camera RAW developing that the D40 premiered, and before the punchy,vibrant Nikon color that the "newer" Nikons tend to have at default levels.
The more-recent Nikons have seen a shift in the way the images look at "default" values; the D70 has the older, lower-contrast look that Nikon's more-advanced users might want from their JPEGs; the D50 on the other hand, was a lot more vibrant, with a snappier contrast to the images, more geared toward those who wanted to shoot-and-show JPEGs.
Of course, the D70 also had the Vivid and Direct Print options, and so it was one of the first Nikon d-slr's that did not produce the dull,murky,almost dingy straight out of camera JPEGs that the Nikon D1 and D100 series bodies used to crank out. Honestly--between the D70 and the D40, I prefer the D40. I would rather have a D3000 or D3100 than a D70 or D70s. The LCD screen on the D70 sucks.