My workplace seems to be big fans of Toad software. I have used Toad as just a support guy for three years or so and have barely scraped the functionality needed by the tool. During an app upgrade a few weeks ago there are a few business people that need to run queries and such against the database so we have created read-only accounts to Oracle to facilitate this…oh yes and the installation of Toad on the user machines was needed as well.
One of the things that I found this week after trying to do a minimal install needed of the Oracle client is that when users need to create an ODBC connection as well that they need to have the Administrator install of the Oracle client. When installing the Oracle client there is first and option to deinstall products (and here I was calling it uninstalling for all these years) which is a good thing to do to get rid of 9.2 or other releases of Oracle that you do not need.
Next you have choices between and instant client, runtime, administrator, and custom installs of the Oracle client. If you need ODBC then from trial and error I found that Administrator install is the minimum that you need to get your TNSNames.ora file to have a place to go.
Oh, and if you have no experience with Oracle clients before, remember to drop the known good copy of your tnsnames.ora file into the \network\admin folder so that Oracle and other interfaces to your application can see it.