Afraid that doesn't make much sense.
First of all.... the webserver calls PHP, not the other way around. You can config your webserver to call a remote installation of PHP, but PHP can't initiate and execute code then pass the results to a remote webserver (that would be a HUGE security hole).
Second, ric was asking about installing IIS on Win98. IIS does not run on the Win9x family, NT only. This is a fact that is indisputable.
Finally, if you're concerned about IIS's pathetic security (which everyone should be) the only way to completely secure an IIS installation is to follow Conexant's advice. Install Apache and use that as your world accessible server. If you must run IIS, have Apache forward requests off to an installation of IIS running on your internal network, receive the output from IIS, and pass the that output back to the client. Thus, as far as any worm or person can tell, you're not running IIS at all and Typhoid Mary won't suffer yet another exploit attack.
YAUFS - Yet Another Usless Flash Site
YAISH - Yet Another IIS Security Hole
-geoff