1. Ganimede/Application Server
Ganimede server component needs to reside on the same machine that you use as Application Server, where your applications source code reside.
For Ganimede server you'll need at least Client Networking product from Progress Software Corporation or one of development suits (ProVision) if you want to do the development - version V9.1A or later. Ganimede need to run progress 4GL in batch mode, so it needs '_progres' executable to be present.
You can also use Ganimede server on the same machine as Database server, then the RDBMS product will be more than enough (WorkGroup or Enterprise RDBMS) as long they are from the V9 family.

2. Web Server
In order to use Ganimede Messenger (cgi-bin) component you need a CGI 1.1 compliant web server - this is the preferred architecture.
You can optionally use one of the following available interfaces: PHP, Python or Zope.

3. Database server
Whatever Progress RDBMS product that you my have, even Development RDBMS that comes with ProVision Plus for testing purposes - version V8 or later (as V9 clients can connect to V8 database server).

* In order to compile the source code you should have a Progress development product - ProVision, for the C coded part of Ganimede you can use your favorite C compiler.