Private Sub Worksheet_SelectionChange(ByVal Target As Range)
If Target.Column 10 Then Set Target =
Target.Worksheet.Cells(Target.Row + 1, 1)
If Target.Row 10 Then Set Target = Target.Worksheet.Cells(1, 1)
Target.Activate
End Sub

This won't let the user enter a cell that is outside the range A1:J10
in the worksheet.

Cheers,
Jason Lepack