Over use of expensive software systems: Over use of expensive software systems

When an organisation purchases an expensive software system there is a tendency to try and use the system to do as much as possible - presumably to try and get value for money. It is a natural reaction, but I think it is the wrong thing to do. I believe it is better to use Open Source Software to perform as many tasks as possible, and to only use the expensive software system for tasks that no other software can do. Then in the future if an open source or cheaper solution becomes available that can replace the more expensive system you won't find yourself locked into the expensive system and unable to make the change to a more economic alternative.