password reset

Hi group,
thanks for your previous response about the DB storage in postgres.

now, I have a question for a password related issue.As you can see I have problems with my pwd.
Either I forgot or misconfigured while installing the DB.I have loged in to XP as the user "vgopal" and it's the Admin account for XP.

C:\Program Files\PostgreSQL\8.1\bin>psql
Password:
psql: FATAL:  password authentication failed for user "vgopal"

what are the options do I have?
1.reset pwd.! how?
2.I can't even create another user/role
(createuser: could not connect to database postgres: FATAL:  password authentication failed for user "vgopal")

Thanks in advance.
BRs,
--Venu