On a fresh php installation (on WinXP using IIS 5) the mysql extension did not load. This turned out to be because php could not find the libmysql.dll library - to resolve just put the php dir (eg "c:\xampp\php) and the ext dir (c:\xampp\php\ext) into the PATH environment variable (and restart iis). To verify your php configuration, create a php file with the following content: <?php phpinfo(); ?> Save this as something like info.php into your web root dir and navigate to it with a browser...
Windows Vista Home edition has some funny quirks - and this one is a prime example... When trying to update my hosts file I get permission denied. That's odd - so I check the permissions and sure enough Administrator group has write access - yet I am the only administror on the system. How's that for tricky - so I'm an admin with no admin rights - go figure. Then I tried deleting the file then readding it.... wow - delete worked but could not re-add. It appears the only way around this little gem...