[postgis-users] Proximity search by address

[snacktime]

Some of this might be a bit off topic.  We have a database of doctors
from all over the us, about a million all told.  We need to create a
proximity search where the user can enter in their address, and get a
list of all doctors within X number of miles.  I'm assuming that if we
store the latitude/longitude of every doctor in the database, and also
have the latitude/longitude of the user, that it wouldn't be too much
effort to calculate proximity?  Assuming that's true, my next question
is how to get the coordinates for the address of the user.  Are there
any existing databases already imported into postgresql?  If not, is
it a huge project to do so, and what would the best source be? (Tiger
??).  Or would we be better off using one of the web api based
geocoding services?


The second part of the project is that we want to display a map of all
the doctors that match the search, preferebly with driving
instructions for each one if possible.  If anyone has any suggestions
in this area that would be great.  I've just started looking at
mapquest, google, and yahoo.

We are also willing to pay for a solution, or partial solution all
depending on the circumstances.  For example if someone has the
address database already in postgresql, and if it will work with the
map solution we end up using.

Chris