Can Excel automatically update a cell with today's date when another cell is edited?

hi ,

This is my first post..i need a help with updating a cell
Can Excel automatically update a cell with today's date when another cell is edited?
for instance if i update/change a value in A1 from 3000 to 300 can i some one help with a formula which can update the current date and time in B1 cell which was with yesterdays date and time..

Private Sub Worksheet_Change(ByVal Target As Range)
Const WS_RANGE As String = "A1"     '<== change to suit

    On Error GoTo ws_exit
    Application.EnableEvents = False

    If Not Intersect(Target, Me.Range(WS_RANGE)) Is Nothing Then
        With Target
            .Offset(0, 1).Value2 = Now
            .Offset(0, 1).NumberFormat = "dd mmm yyyy hh:mm:ss"
        End With
    End If

ws_exit:
    Application.EnableEvents = True
End Sub

This is worksheet event code, which means that it needs to be
placed in the appropriate worksheet code module, not a standard
code module. To do this, right-click on the sheet tab, select
the View Code option from the menu, and paste the code in.