I love my D50 too. I would like the bigger viewfinder and added
features of the D80.  We will have to wait to make a judgment on  image
quality, other than resolution, and see more pictures and test results.
I will be surprised if the D80 has lower noise or better dynamic range
than the D50 with its smaller pixels.  It might though be able to match
the d50, which would be excellent performance fro a 10mP 1.5x sensor.

For anyone who is interested I have posted a review of the D50 here:

http://www.digitaldingus.com/forums/viewtopic.php?t=3029

and a review of the Nikon 18-200 VR with links to many other reviews
here:

http://www.digitaldingus.com/forums/viewtopic.php?t=3033

Generally I'd say yes.

But go to a camera store and check out the D200 viewfinder. That should
give you some indication.

We don't know yet...a proper hands-on review of a production model has
yet to be posted on the internet.

I've seen a few sample high ISO images that are promising, but they're
not always representative of actual performance.

Without actually using the new camera one can only speculate. I can say
that I do a lot of low light photography and find a large bright
viewfinder critical to getting good images. That and bright fast glass
that allows more light to reach the mirror.

For my purposes the difference in megapixel count between the D50/70 and
D80/200 is not a dealmaker as the dynamic range of the sensor is no
different. Noise levels at normal ISOs are already amazingly low for these
early (in the sense that this is the beginning of the digital photo age)
sensors and I rarely use high ISOs anyway.
One downside for me for the D80 is that it does not use compact flash cards.
For those of us with gigagbytes worth of those cards this can be a
significant added cost.
The major upside for the D80, and it could be a can't live without
dealmaker, is a better viewfinder than the D70. The D70 is the best camera
with the worse viewfinder ever made.

Yes.  The more light, the better you see.  The better you see, the
better you focus.

Some AF cameras also have focus screen options for manual focus that
allow greater focus control at the expense of some light.  So a brighter
viewfinder offsets the loss.  I don't know if the D80 has focus screen
options.

The LCD, even in closeup, is not a great way to verify focus.  It will
show obvious blunders, but is too small to analyze DOF critically.  IOW
what looks okay in the LCD may look slightly off in the print.  Best to
work on your technique and be absolutely sure the diopter setting of the
viewfinder is correct for your eyesight.  Make sure your shooting with
your dominant eye ('right' for about 2/3 of people).

To determine the dominant eye, locate a small object across the room.
With both eyes open, bring your hand up at arms length with your thumb
up.  Cover the far object with your thumb.  Stay still.  Close one eye
then the other.  The eye that has the thumb and the object aligned is
the dominant.

Cheers,
Alan

I think so yes, that's the biggest difference when I upgraded from a D70
to a D200 was being able to actually manual focus and judge DOF. And yes
the D200 LCD is much bigger with much better controls to zoom into full
pixels with a couple clicks & a a twist of a dial. I don't know whether
the D80 will have those same specs but those have been a big improvement
for my work. Take a close look at the functions & body controls when a
D80 becomes available, there are lots of functions on the D200 that give
me much better control, like for example the ease of zooming on the LCD
& 3 color histogram, more knobs on the body to change ISO visible in the
viewfinder, etc.

I recently got an angle finder for my 20D and it magnifies the
viewfind...big difference. These old eyes were finding manual focus
a bit daunting and a bigger view helps alot - for manual focus; and
when i would normally use auto but the light doesn't allow it to
work properly.

size matters

cheers