Question: Who's Using Postgres

Good Morning Everyone,
I have a general question about who is using Postgresql.  This is not a
marketing survey and any information I collect will only be used by me.
 Here's the background.
I have a user who has developed a Visual Basic application that uses MS
Access files for it's data storage.  Currently, this datafile is about
fifty megs in size.  There are about fifteen users who use these files in
the application, needless to say, this is having a severe impact on our
network.  After much heartache and pain, I was able to convince him that we
need to look at a RDBMS to put the data on.  Of course, I suggested
Postgres as an alternative to MS SQL server for many reasons.  Linux runs
on all of my servers, I'm happy with it's performance and reliability.  I'm
currently running Postgres as my web server's backend.  Opensource software
does not scare me.  However, his side of the camp comes from the Windows
world.  "It has to be MS SQL server.  It'll be easier to program to than
any other server." "Opensource software isn't going any where." "Can we
depend on it?" are common questions and statements I have heard.
I am not trying to start a ruckus or a flamewar, but I would like to know
who's using Postgres out there.  What's the application?  How big are your
databases?  Are you using Visual Basic or C to connect to it through ODBC
or are you using a Web interface?
Any information you can provide will be greatly appreciated.
thank you
Corey W. Gibbs