Timestamps (binary) and SQL-Server/ADO-Clientside but using queries/Delphi

I'm using SQL-Server 2k and Delphi-ADO/ClientSide Cursors but use queries...

I populate a combobox with all the records.  

I have included a timestamp column in my table.  ( i understand its not for date/time values)

What i need is whenever I select an item from the combobox, to check if the time stamp changed from the last time it was read, and if that's true then to remove and reinsert the value inside the combobox... At the moment i'm doing it like this:

x := Combo.ItemIndex;

if Combo.Text <> Query.FieldByName('ColumnName').AsString then
   begin
      Combo.Items.Delete(x);
      Combo.Items.Insert(x,Query.FieldByName('ColumnName').AsString);
      Combo.ItemIndex := x;
   end;

But i need to use TimeStamps...

Any ideas appreciated...