Installing ODBC driver manager (top level driver)
install unixODBC driver manager for Linux platform (WIN32 already have ODBC driver manager)
yum install unixODBC
tested configuration:
- unixODBC-2.2.9-1 for Fedora Core 3
- unixODBC-2.2.11-1 for Fedora Core 4
install ODBC driver for specific database (low level driver)
Linux/Postgres (do not use packages from yum, they are too old for Fedora Core 3/4, for 5-7 you can try but make sure that it will install 08.xxx version)
There is a source rpm on sam:/u2/programs/databases_and_odbc/postgresql-odbc-08.01.0200-1.2.src.rpm for Fedora Core 3 or 4 there are prebuild odbc on sam (Core 3) and fuzzy (Core 4). Just mount them somewhere somehow and do make install. Otherwise have a FUN 
on Fedora Core 3 cd sam:/u2/vlad/psodbc/psqlodbc-08.01.0200 make install on Fedora Core 4 cd fuzzy:/home/postgres/psqlodbc-08.01.0200 make install
- Win32 connected to Linux/PostgreSQL server:
download driver and other stuff from http://pgfoundry.org/projects/pgw32cli/, then follow instructions
- Win32/MSSQL and */Oracle have drivers included in server or client packages
Check http://www.savelono.com/linux/how-to-configure-linux-odbc-connections-for-ms-sql.html for ms-sql connection with freetds