not an expert but my suggestion would be to use the before change  event to
save the old value... or maybe it's the on enter event.... not exactly
sure.. again i'm not an expert ...

Yes, there is a way. Use the worksheet  SelectionChange Event. Within the
VBE go to the worksheet in question, for example  Sheet1. In the drop
down box above the VBE environment, where it normally says "General",
select "Worksheet". In the drop down box to the right select
"SelectionChange".

Or just copy and paste this into the Sheet Module.
Private Sub Worksheet_SelectionChange(ByVal Target As Range)

The "Target" value grabs anything the user  clicks on, within a cell  that
is. So now something like this...

Dim sHold as Variant
sHold = Target.Value

...will grab what's in the cell before you change  it.

Just for reference, if anyone else is interested - declare a module
level variable in the General declarations section to pick up the
value.

You can then access  this value in the change  event to see what the
old and new values are.

One last point to consider, you will get an error if you have this
code and the user  selects more than one cell  so a good idea to trap
for target.cells.count > 1.