Lightweight web server for Windows?

What do people on this list use as an ultra-lightweight web server (with PHP capability of course) on Windows? I have an old but still well functioning laptop that I have just given a second life by installing Windows Fundamentals (a stripped down version of XP). This works surprisingly well. So now I am looking for the necessary software, so I can do some local programming. Some requirements I can think of: - Extremely small memory footprint and fast efficient code. This laptop still works well but it can certainly use some help! - Both free as in beer and free as in speech would be my preference. - Be able to run as a "service" in XP. - Be able to run PHP (obviously) and perhaps a few other nice server features, like SSI and name based virtual hosts. Any suggestions? I have not seriously used Windows for years now, so my knowledge of that platform is not exactly up to date anymore. I am used to dealing with Debian/Ubuntu Linux and Apache but not much else, frankly. Apache does seem to heavy for this. My initial thought was to install Lighttpd under Cygwin, but perhaps I would be missing out on some great little server program that I have not yet heard about.