Hi,
please post some example code that runs slow.
Besides that I had two W2K3 systems with similar symptoms. The solution was to enable output_buffering in php.ini by setting e.g.
output_buffering=4096
Then restart apache. But I faced that problems with IIS only so the problem could be the code.
Additionally, set error_reporting to E_ALL in php.ini (if not already set to E_ALL) and check if you see any error messages.
Thomas