If client is running Windows2003 server

[Websitetuner]

Hi,
My client is running win2003 has, php, mysql cababilities. I'm working on a content management system that will be uploaded to their server.
My question is: Should I use the Windows version of XAMPP if the client's application will eventually be uploaded to that type of server? Or does it not matter?

I know this sounds like a no brainer, but I am currently using XAMPP/linux as my test server because 99.9% of my clients are on Linux servers.

/Thank much,
Monica