Changing an Excel Data Source

I have a workbook in Excel 2007 that uses a data connection. Originally I had this connected to an Access DB and it filled one of my sheets' tables with data. I have since transitioned the DB to MS SQL server. I have no problem removing the old data source and adding the new one, but how can I modify the sheet/table so that it picks up the new data? That sheet's data connection buttons gray out.

I'm trying to avoid all of my formulas changing to #REF! when I delete the sheet/table.

Thanks

Do you have your workbook protected?