Please make sure you use fcgiconfig.js the followingway to modify the settings of your fcgiext.ini file and scriptmaps
/system32/inetsrv/fcgiconfig.js -add -section:"PHP" -extension:"php" -path:"<path to php-cgi.exe>"
After this your fcgiext.ini file should look something like this
[Types]
php=PHP
[PHP]
ExePath=<path to php-cgi.exe>
Also, the scriptmaps on your IIS 6.0 server will have an entry mapping *.php to /windows/system32/inetsrv/fcgiext.dll
If you still get an Access Denied error after this, it is possible that the fastcgi.impersonate = 0 in the php.ini file.
Hope this helps
Thanks
Yamini