folder security

Hi,

I'm hosting a lot of applications that runs their own site/app pool, hostnames and own installation folder. *IIS7.5*

Almost all of the application pools runs under its own domain user account.

Do I need to have iis_iusrs or iusr added to the security on the folder or will it be enough to just have the domain user that the pool runs as?

I'm trying to achieve the best security for each and every application so that the applications only have access to its own files/folders etc.

Thanks in advance