What kind of machine are you running? If you're on Windows, (which is about the only thing that can run ASP), you need IIS (yet another M$ product). If you look around, there are plenty of guides on installing PHP on IIS, alongside with ASP.
As for Apache not supporting ASP, it supports some perversion of ASP commonly known as Apache-ASP. I still don't get what that is, if someone can explain it, I'll appreciate it.