install IIS ISAPI

Hi, I use to install PHP under IIS as a ISAPI module. So I add a ISAPI filter and define a new App mapping in 'configure' When looking at the documentation (see http://be.php.net/manual/en/install.iis.php, "Windows NT/2000/XP and IIS 4 or newer") I can read : "If you don't want to perform HTTP Authentication using PHP, you can (and should) skip this step. Under ISAPI Filters, add a new ISAPI filter. Use PHP as the filter name, and supply a path to the php4isapi.dll. " If I understand well, we should skip this step whe possible. I don't use HTTP authentcation, but I always add a ISAPI filter to my IIS config. Why should we avoid this?? I tried to remove the ISAPI filter and restart IIS. Everything seems Ok Vincent