protect a sheet

hello
i want to enable a user change data on a sheet but not formulas.
[VBA]
Dim cell As Range
For Each cell In ActiveSheet.UsedRange
With ActiveSheet
.Unprotect
If cell.HasFormula Then
cell.Locked = True
Else
cell.Locked = False
ActiveSheet.Protect
End If
End With
Next

[/VBA]
is it possible to do it?
thanks

[vba]

Dim cell As Range
For Each cell In ActiveSheet.UsedRange
With ActiveSheet
.Unprotect
cell.Locked = cell.HasFormula
.Protect
End With
Next
[/vba]