I have a D50, D90, and D7000. The D50 was my first DSLR, which I used for five years, and still use today. It's a great camera. But,...the D7000 is to a D50 what a 2013 60" flat screen TV is to a 25" 1970 tube TV. So many orders of magnitude better as to be incomparable.
The D50 is noisy at it's highest ISO (1600). I regularly shoot basketball images at ISO 4000 on my D7000 that look better than anything I could get from the D50 at ISO 1600. The D7000 shoots 6FPS vs 2.5 FPS on the D50. The D7000 sensor has far greater dynamic range and far better cropping ability. The D7000 has a great, accurate, 3" LCD. The D50 has a useless dinky little LCD that shows inaccurate colors. The D7000 has custom setting modes on the dial, and the ability to use two SD cards. The D50 cannot use cards above a certain size (Don't remember but I think it might be 2GB?), and it holds only one card. The D7000 also has more control buttons, minimizing the need to use menus.
The good: the D7000 controls are laid out similarly, and take almost no transition time from a D50/D70/D90.
The bad: As stated above, the D7000 resolution takes a lot of learning curve (and mine was from the 10MP D90). 16 MP is MUCH less forgiving of bad focusing technique and slow/inaccurate focusing lenses than a D50. Expect to pull some hair out making the transition, or adapt your technique quickly.
But, the D7000 is a better camera that will make you a better photographer if you learn to use it.