I am not able to locate Application Stack Builder on this step:
After you install 8.3 there is another window that opens called the application stack builder. If you have closed this window, you can open it again using the Start menu > Programs > PostgreSQL 8.3 > Application Stack Builder.
The only options I have are:
Configuration Files
Documentation
Command Prompt
PGAdmin III
psql to postgres
Reload Configuration
Start Service
Stop Service
