The Tungsten W won't work at all above about 2000' MSL, from my
experience. This is due to the fact that it uses the cellular network
(specifically, AT&T's GSM/GPRS network) as opposed to the Palm i710
which uses the Mobitex network. Since Mobitex uses omnidirectional
antennas (it is more of a paging network), those antennas have lobes
that allow coverage up to FL410 in certain spots. The cellular
hnetworks use corner reflectors which focus a lot fo the signal energy
on the horizon and lower angles (some of the antennas have downtilt,
depending on how they are trying to contain that particular cell's
coverage.

However, the Tungsten W is a great device and I believe there are some
decent sales on it right now. Great for picking up weather on the
ground and at low altitudes. I use Adds (from NCAR) and CBAV for
weather radar.

-Dave