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;