Suunto Vector's Barometer

While I have read a number of thread about the Suunto Vector, I am still
a little confused about the operation of the barometer. I got a new
Vector over the weekend and I really want to be able to understand it's
operation.

From the rather weak manual that came with it I know that there are 4
barometer screens (or sub-modes, as Suunto calls them).

1. The main screen
2. The pressure difference measurement screen
3. 4-day memory screen
4. Sea level screen

What I am confused about is the how the barometer reading on the main
screen (1) differs from the reading on the sea level screen (4). For
example, right now (4/26/2005 in Salt Lake City, UT)the main barometer
screen read 24.85 inHg while the Sea Level screen reads 29.20 inHg.
NOAA.org says the reading should be around 29.85 inHg at the SLC
airport, about 1800 ft. lower that I am right (so that's pretty close).

What is the main barometer screen(1) really telling me? And why doesn't
show a reading closer to what the local weather says it should be?

Could this watch be defective?

Also, I calibrated the altimeter using a known altitude, rather that
adjusting the Sea Level pressure. As I understand it, this will give me
a more accurate altimeter reading. Correct?

Thanks,
Jason