[Az-Geocaching] GPS: problem locking on enough satellites and more

[Monika]

Hello,

I am new to this list as well as to GPS. My question is a little off topic,
but hopefully I can get some pointers from you anyway. 
I just got my hands on Magellan's GPS 4000, which is an older model, but it
does have a set of nice navigational capabilities, which I wanted to use
during my upcoming trip.

These capabilities require however a minimum speed (at which the
receiver must travel) and thus are ideal for car travel. Unfortunately car
roof obscures view of the sky and over 95% of time the receiver cannot get a
lock on enough satellites. (Placing it on a dashboard did not help). Do you
know of a way to get around this problem?

I also wanted to get a few positions from a map before I leave. 
I have found this web page:
http://www.juggling.org/bin/un.cgi/map-find
which gives latitude and longitude of given location, but it does not give
altitude. I was also told that such sites provide usually poor accuracy.
Do you know where I could access good quality on-line maps with latitude,
longitude and altitude? If not, then do you know of a bookstore or another
place in Phoenix area, which would carry good quality cartographic materials
(which are not terribly expensive)?

thanks,
Monika