WinXP installation

I need some help please! I'm using PostgreSQL for a long time (about two yeas), but always in a Linux box. So, I always could install and use it with no major problems!
Unfortunetly now I have to use it on WinXP. So, here is my problem:

I intalled PostgreSQL 8.0.3 in WInXP (SP1) with administrator rights, as a service and had confiured the user postgres for the system and a user postgres for the database.
So far, so good! I known that I connot start the service with administrator rights!
But when I try to start the service with another user it give me this error:

2005-06-08 15:14:07 NOTICE: Unknown win32 socket error code: 10106
2005-06-08 15:14:07 LOG: could not create IPv4 socket: Invalid argument
2005-06-08 15:14:07 WARNING: could not create listen socket for "localhost"
2005-06-08 15:14:07 FATAL: no socket created for listening

Please I really need some help! Any ideas?
Thanks!!