installing on windows 2003

k i have installed and hava postgres running on xp for 8 months now...

but i have recently purchased a server and running window 2003 on it..

i install postgres using "PgSQL731wina1.exe"

it installs but i get this error at the end which i think is related to my problem (which i will expain in detail)

my name is "Administrator"
computer name is "NsxBox"

error message is

"chown: ' Administrator.unknown': invalid group
In: '/bin/postmaster': File exists
initdb:You must identify where the data for this database system will reside
"
then it asks me to enter a password for "NsxBox/Adminstrator" (i set it to "")

i am logged in as Administrator
there is no group called Administrator but there is a group called Administrators.. if i change the name of the group to Administrator in windows i still get the same error..

after tinking with postgres just so when i start the service to stay opened (the cmd window would open and close fast with error)

i get postmaster start sucessfully .....database is ready.....

then i try to create a test database by do "createDb test"

i get the error
"pgsql FATAL user 'Administrator' does not exist
createdb: database creation failed"

i cannot create a user cause postgres thinks that 'Administrator' is not a valid user... i tries su postgres but the don't work either...

but if i go
su Administrator
it let me but i need to enter the password ..i enter in "" and it tells me that the password is incorrect..

can someone steer in the right direction..any help would be much appreciated...if you need more details just ask...thanks in advance...