Hi Cluless,
Sorry to hear that you have having trouble with Postgres and PostGIS versions. Finding back versions of these two apps is a bit of an unresolved issue. On linux platforms where most of the users and developers of these products operate, finding back versions is not much of a problem, but on windows it is the experience you had encountered.
We have had some conversations with the Postgres folks and now the Enterprise DB folks and they maintain that if you fiddle with their folder structure on the website long enough you will find the version of Postgres at least, that you seek. But I have never been successful. This is why we distribute the main version of Postgres that we support. Would you be able to use the provided 8.3.8 version? Unfortunately we are not able to distribute PostGIS so I can not offer you anything on our media, for that application. Have you thought of contacting or commenting on the Refractions Research blogs?
In theory if we certify a major version of Postgres (like 8.4.1) then its minor versions should not have changed anything that would break our st_geometry.dll but in practice that does not always work.
Wishing you the best,
Sincerely,
Kasia