PostGIS 9.2 is installed along with OpenGeoSuite using one click setup. But 9.2 dont support pgRouting. So I need to install 8.4. I dont how to include binaries and all. So someone please tell me how to install it in windows 7 64 bit in detail including what port etc.
It's PostgreSQL 9.2 not PostGIS 9.2, PostGIS is just an add-on for Postgres. You should check this thread for Windows 9.1 packages: http://gis.stackexchange.com/a/26830/16594. 9.1 is a much better choice than 8.4. Also there is a dev package for 9.2 here: http://www.postgis.net/windows_downloads so probably a stable one will come up soon and it'll be easier to upgrade from 9.1 than from 8.4