Configure PHP for safe use on web farms

We operate an "instant" type web hosting service, along the lines of GeoCities, where the user's web address is like [login to view URL] We currently offer no scripting abilities on the site, but would like to add PHP which has been requested by many users. The catch is all users (30,000) operate under the same username, and don't run under separate virtual "directories", we don't want people able to write scripts which can browse/access other people's files. We also don't want to setup/administer tens of thousands of virtual web sites or virtual folders on our IIS boxes. This is NOT a request for the user administration or for a web front-end for users to manage their accounts and files, but for the ability for our users to be able to use CGI. We want to install/configure PHP to limit file access to their own directories, and to cover any other potential security problems. If this will require minor changes to the system's design that is a possibility. We are open to suggestions, comments, etc. ## Deliverables 1) Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. 2) Installation package that will install the software (in ready-to-run condition) on the platform(s) specified in this bid request. 3) Exclusive and complete copyrights to all work purchased. (No GPL, GNU, 3rd party components, etc. unless all copyright ramifications are explained AND AGREED TO by the buyer on the site per the coder's Seller Legal Agreement). ## Platform The platform is a load balanced (sticky sessions) farm of W2K3 boxes running IIS 6 with content located on network-attached storage.