What are the advantages and disadvantages of php on IIS?
or
What are the advantages and disadvantages of running php on Apache?
possible duplication: apache-vs-iis-php-performance-comparison
There are so many resources available on the Internet to help you summarize the comparison:
for starters you will have enough information.
I know about problems downloading files via php to a Windows server. If the temp directory is not set correctly, the resolution of the downloaded files will also be incorrect.
http://au.php.net/manual/en/function.move-uploaded-file.php somewhere in the comments.
Apache is better, many php applications should use apache mod. for example: url_rewrite