uses Registry; 

procedure TForm1.GetDataSourceNames(System: Boolean); 
var 
 reg: TRegistry; 
begin 
 ListBox1.Items.Clear; 

 reg := TRegistry.Create; 
 try 
 if System then 
 reg.RootKey := HKEY_LOCAL_MACHINE 
 else 
 reg.RootKey := HKEY_CURRENT_USER; 

 if reg.OpenKey('\Software\ODBC\ODBC.INI\ODBC Data Sources', False) then 
 begin 
 reg.GetValueNames(ListBox1.Items); 
 end; 

 finally 
 reg.CloseKey; 
 FreeAndNil(reg); 
 end; 
end; 

procedure TForm1.Button1Click(Sender: TObject); 
begin 
 //Системные DSNs 
 GetDataSourceNames(True); 
 //Пользовательские DSNs 
 GetDataSourceNames(False); 
end;