function SystemErrorMessage: string;
 var
 P: PChar;
 begin
 if FormatMessage(Format_Message_Allocate_Buffer + Format_Message_From_System,
 nil,
 GetLastError,
 0,
 @P,
 0,
 nil) <> 0 then
 begin
 Result := P;
 LocalFree(Integer(P))
 end
 else
 Result := '';
 end;


 // Path to Original File 

procedure TForm1.Button2Click(Sender: TObject);
 begin
 if Opendialog1.Execute then
 edit1.Text := OpenDialog1.FileName;
 end;

 // Path to New File 

procedure TForm1.Button3Click(Sender: TObject);
 begin
 if Opendialog2.Execute then
 edit2.Text := OpenDialog2.FileName;
 end;

 // Replace the File. 

procedure TForm1.Button1Click(Sender: TObject);
 begin
 if (Movefileex(PChar(Edit1.Text), PChar(Edit2.Text), MOVEFILE_DELAY_UNTIL_REBOOT) = False) then
 ShowMessage(SystemErrorMessage)
 else
 begin
 ShowMessage('Please Restart Windows to have these changes take effect');
 halt;
 end;
 end;