Sub ProtectFormulas()
Dim ws As Worksheet, rng As Range
Set ws = ThisWorkbook.Sheets("Protection")
ws.Unprotect
' Get each used cell in the worksheet.
For Each rng In ws.UsedRange
' If it contains a formula, lock the cell.
If InStr(rng.Formula, "=") Then
rng.Locked = True
' Otherwise unlock the cell.
Else
rng.Locked = False
End If
Next
ws.Protect "Excel2003"
End Sub