If you used a Command Text to set the query for the report, you're probably ok. If you used the Database Expert to select tables and link them, you may have problems due to the table owner being included in the SQL. Use the Database menu option "Show SQL Query" to take a look at the SQL in your report. If there is "sa." in front of the table names, just changing the driver will not work because sa is not a valid table owner in Oracle.
-Dell