Given that it comes with CentOS4, and FC4 by default (which work with PSA), and my packages are backports from FC4 and CentOS4 I'd say yes (Im on PSA 7.5.4). Im running PHP5 on all my systems, from RH9 to CentOS4. The only thing I know of for a fact that does not co-exist with 5.0 is oscommerce. I dont use it myself, so I couldnt tell you if the version in PSA 8 works with it or not.