PostGres 8.3.7 installation issues on Windows Vista Home Basic

Hello

I tried to install PostGres 8.3.7.
It installed OK but hung on trying to install the GIS database. I felt that the GIS installation was hung because the postgres ID had a password which the GIS installation process did not seem to use.
So, I removed the password for the postgres ID from the admin application. It allowed me to do so but future logins (connect) were impossible.
So, I tried to uninstall postgres to reinstall but it creates some directories e.g. pg_log which are totally inaccessible, even after disabling user account security and giving all perms to the 8.3 and below dirs to my ID. Just cannot delete the dir 8.3 under Program Files\postgresSQL.

So, I am stuck as reinstallation fails due to existing dirs.
Wonder how to cleanup and start over again.
Also, if I setup a password for the postgres ID, how does the GIS database install know about it?

Thanks