{
 With different versions of MDAC available it is sometimes
 useful to know that your application won't fail because a user
 hasn't got the latest version installed.
 The following function returns the ADO version installed,
 you need to place ComObj in the uses clause to use this function.
}
function GetADOVersion: Double;
var
 ADO: OLEVariant;
begin
 try
  ADO := CreateOLEObject('adodb.connection');
  Result := StrToFloat(ADO.Version);
  ADO := Null;
 except
  Result := 0.0;
 end;
end;
// To use this function try something like:
procedure TForm1.Button1Click(Sender: TObject);
const
 ADOVersionNeeded = 2.5;
begin
 if GetADOVersion then
  ShowMessage('Need to install MDAC version 2.7')
 else
  ShowMessage(Format('ADO Version %n, is OK', [GetADOVersion]));
end;

function TfrmMain.GetADOVersion: Double;

var

 ADO: OLEVariant;

begin

 try

  ADO := CreateOLEObject('adodb.connection');

  Result := StrToFloat(ADO.Version);

  ADO := Null;

 except

  Result := 0.0;

 end;

end;