Adopting PHP Code to a UNIX/Windows Environment?

Pointy Haired Programmer queries: "I work for a Fortune 100 company that is currently using a mixture of *NIX web servers and MS web servers. This company is very slow to adopt any new technology that isn't MS. So, we are serving most of our pages either through ASP or some type of CGI. Right now, we are investigating the possible use of PHP on our network due its cross platform abilities. I really want to see this happen for us, as I am an avid supporter of both PHP and Apache. I was wondering what the Slashdot Community had to say about the situation and maybe some of the advantages and the disadvantages of PHP being deployed in such a manner." Not having used PHP before, I'm not quite sure how well the code adapts to changes in its environment. Are there any "gotcha's!" that one needs to worry about when taking PHP code from Unix to Windows and vice-versa? How well does PHP work on Microsoft Servers?