This information is stored under the "HKEY\CURRENT USER" section of the Windows registry. The task of retrieving this entry is greatly simplified by using the TRegIniFile component. Example:

uses Registry;
procedure TForm .Button Click(Sender: TObject);
var
  reg: TRegIniFile;
begin
  reg := TRegIniFile.create('SOFTWARE\MICROSOFT\MS SETUP (ACME)\');
  Memo .Lines.Add(reg.ReadString('USER INFO',
                                 'DefName',
                                 'Frank Borland'));
  Memo .Lines.Add(reg.ReadString('USER INFO',
                                 'DefCompany',
                                 'A Valued Borland Customer'));
  reg.free;
end;