Password authentication fails

Hi -
I know this is a newbie question, so forgive me
I've never used postgres before, but i've recently installed it and the pgAdmin tools on my XP box. I installed it as a service using a set of what appears to be pretty decent instructions online. Everything went smoothly i thought - i created a service account and a superuser account. But when I start the service and try to connect from within the pgAdmin tool console, I get a fatal error saying that my password authentication failed. One thing I noticed when I right click on the server I just created, and look at the properties is that the password field is empty and grayed out. I would at least expect to see the password contents as a secret field, like "*********", even if it is grayed out.

I can start and stop the service in pgAdmin, and I can see the service running. I know I must be doing something or not doing something simple, so any help would be appreciated. Thank you.

- Joe