There is an excellent article on ERP from IBM that discusses the issues of the value of ERP. Getting everyone communicating together is one of the largest benefits of implementing an ERP system.
Using ERP to get everyone on the same page
By Julie Fraser
How many different applications are in use across your organization? Most small and medium businesses have dozens if not hundreds of different systems. The result: critical information is not being shared among departments, and employees struggle to get visibility to what is correct or what has happened. The cost of manually tracking down information is considerable. When you consider that it also leads to missed opportunities, poor decisions, poor execution, and disjointed customer service, the cost is far higher than many companies realize.