Help connecting

Hi,

I am somewhat of a Linux novice and downloaded postgres the other day 
and now pgadmin III.  Having trouble connecting via pgadmin3.

System - Ubuntu Linux 5.04
postgres - 7.4.7-2ubuntu2.1

Using the command line psql I can get to the test database ok and see 
the test table and sequence I created, plus users I've created via 
command line. 

When I try to  "add server" via pgadmin3  it just hangs up and has to be 
killed.  Dialog box & info is:
Address - 127.0.0.1
description - testdb
service - I left blank (what to put there?)
port - 5432
SSL - didn't touch
initialdb - test
username - myusername
need password - checked
password - my password

I've probably done something wrong, but not sure what. 

thanks,

Phil J