Unable to add server in PGadmin

Hi,
I have installed postgres 8.2 on a Windows Vista machine.
PGAdmin came along with the installation and on opening PgAdmin there is a
POstgresSQL DATAbase Server 8.2(localhost:5432) server running on it.
I have another windows machine XP and i have PGadmin installaed on it too.
I am trying to add a server to this PGadmin so that i can access the Vista
Postgres server remotely.
Before when the postgres was running on a linux machine i didnt have any
problem connecting to it with my PGAdmin client (i had the ip address of my
windows XP machine in the pg_hba.conf added).
I was following the same with the Vista machine too...
But ia m unable to connect to Windows Vista machine from Windows XP -
Pgadmin "Connection to database failed." is what i get and the add server
window pops up again.
I am pretty new to postgres installation on windows and is there any thing
else i need to do with the configurations..

Thanks in advance,
Manoj