This may not be what you want to hear, but my own thoughts would be to either roll back to the last 4x PHP or, better yet, install Apache with PHP and MySQL and keep your IIS for serious ASP-ing.
I never like running PHP under IIS. The results for some advanced scripting can be less than optimal, although for general work it's OK.
Call me old fashioned and yes, I know it works (ish), but for any serious work I like PHP and MySQL running on Apache and I keep ASP and .NET stuff running on IIS (sometimes ColdFusion too).
Another consideration is that PHP 5 is largely pointless to use at present unless you're ramping up your skill base for future development - you won't find many hosts offering it for quite some time and getting it to run on IIS (as you've found) is less than easy.
If you want to follow your current path post to that effect - we might have to start application mapping and all kinds of other junk. Any Googling will produce plenty of tutorials on this - some of them even work - click here
I'd suggest a simple WAMP bundle, change its listen on port settings to a port over 80 (ISS uses it by default) and off you go. Try click here for a 'proper' server and if you want help with it just ask.
How did you install PHP and MySQL ?
Have you installed phpMyAdmin click here or the excellent MySQL Administrator click here
A bit more info on what you installed and how you installed it would help. I'm assuming you chose the *shudder* CGI PHP installer.