pgadmin fails to connect

I'm so excited about getting postgres running on my windows xp.  Installed
pgadmin fine. Installed cygwin, installed and started postgres ok... or so I
thought.  But then I had a connection problem from pgadmin and, from reading
the documentation, it seems that I've made the common error of forgetting to
configure the server to allow TCP/IP connections.

From pgadmin, I get the error:

psql: could not connect to server: Connection refused
        Is the server running on host "127.0.0.1" and accepting
        TCP/IP connections on port 5432?

I've tried starting the postmaster with the -i option.  I looked at the
documentation and, in cygwin, the command line I used was:

postmaster -i -D /usr/local/pgsql/data > logfile 2>&1 &

But still no joy.  I'm sure it must be a simple thing... any advice
appreciated!

Helen