procedure TForm1.FormCreate(Sender: TObject);
var
a: array[0..100] of char;
b: dword;
begin
windows.GetVolumeInformation('c:\',a,100,nil,b,b,nil,0);
edit1.Text:=string(a);
end;

procedure TForm1.Edit1KeyDown(Sender: TObject; var Key: Word;
Shift: TShiftState);
begin
if key=vk_return then windows.SetVolumeLabel('C:\', pchar(edit1.Text));
end;