install postgre on windows XP, service failed to start.

I installing postgre SQL on Windowx XP

Product: PostgreSQL 8.1 -- Error 1920. Service 'PostgreSQL Database Server 8.1' (pgsql-8.1) failed to start.  Verify that you have sufficient privileges to start system services.

I got this error when I try to install postgresql on windowx XP

i am using the installer version which is from:

ftp://ftp5.us.postgresql.org/pub/PostgreSQL/binary/v8.1.3/win32/postgresql-8.1.3-1.zip

The user account that the service is created by the installer. I just wonder why it cannot start the service with that account(postgres)

any hits are appreciated

Regards
Jeff