If you have some problems to install PostgreSQL 8.3 you have to look here.
I had problem to install it but now i have fixed them.
First of all before installing the program you have to do :
1) Go to My PC> Control Panel>Administration Tools
2) Open "Services"
3) Look for service' name "Secondary Logon"
4) Start it manually
And now you can install it and you are not goint to get this message "The Secondary Service is not running.This Service is required for the installer to initialize the database.Please start this service and try again"
I hope you can install it now.Bye and good luck