HKey -> String

const
  HKEYNames: array[0..6] of string =
    ('HKEY_CLASSES_ROOT', 
     'HKEY_CURRENT_USER', 
     'HKEY_LOCAL_MACHINE',      
     'HKEY_USERS',
     'HKEY_PERFORMANCE_DATA', 
     'HKEY_CURRENT_CONFIG', 
     'HKEY_DYN_DATA');

function HKEYToStr(const Key: HKEY): string;
begin
  if (key < HKEY_CLASSES_ROOT) or (key > HKEY_CLASSES_ROOT+6) then
    Result := ''
  else
    Result := HKEYNames[key - HKEY_CLASSES_ROOT];
end;