Problems running PostGreSQL silent install

I have seen many problems like this in the forum, but cannot see a solution
for mine...

I have created an account with restricted privileges for the service.
Everything works fine until I get an error running the silent install.

Failed to run initdb: 1!

I then check the logfile, and it says

The files belonging to this database system will be owned by user
"postgres2".
This user must also own the server process.

The database cluster will be initialized with locale C.

initdb: directory "C:/Program Files/PostgreSQL/8.1/data" exists but is not
empty
If you want to create a new database system, either remove or empty
the directory "C:/Program Files/PostgreSQL/8.1/data" or run initdb
with an argument other than "C:/Program Files/PostgreSQL/8.1/data".

The problem is, that I am trying to install a second instance of PostGreSQL
on another port in another location my test computer.
Is this possible?

Here is my silent install .bat script file

msiexec.exe /i postgresql-8.1-int.msi /qr INTERNALLAUNCH=1
ADDLOCAL=server,psql BASEDIR="c:\postgres" SERVICEDOMAIN="%COMPUTERNAME%"
SERVICEACCOUNT="postgres2" SERVICEPASSWORD="test" SUPERPASSWORD="o2BS#9798"
LISTENPORT=9092