How do you convert Quickbooks Enterprise 9.0 backup data to use in Quickbooks pro 2010?

You cannot downgrade from Enterprise to QuickBooks Pro or Premier just using QuickBooks. There are third party applications that have been developed that may be able to do this for you.

Most of the third party applications available on the web that transfer transactions from one company file to another rely on the QB SDK to transfer data. Unfortunately the QB SDK does not support all transaction types so they can not transfer everything. There are several companies that do offer a conversion service that can convert an enterprise file to pro or premier without losing any data.