Step1: Install PostGIS with Spatial database support extension
i. If PostgreSQL is already installed è Launch ‘Application stack builder’ from startup menu in windows 7.
ii. Select the appropriate instance of PGSQL from dropdown list and Click NEXT.
iii. Expand ‘Categories’è Expand ‘Spatial Extensions’ è Select appropriate PostGIS version(1.5) for the already installed PGSQL version(8.4).
iv. Follow the instructions to install the PostGIS extension.