Excel Mime Type

I am creating a web-based application and the PHP server needs a bit of information that is provided by the browser, the mime type of a file upload, particularly an Excel file.

In Safari 3, on my Mac, the mime type for .xls files is application/vnd.ms-excel and using this in my code works perfectly. However, I'm not sure this is the same for a Windows based Safari 3. This would change wouldn't it? Im guessing that the mime type for Windows is application/excel but I would like confirmation please. Can someone confirm the mime type for .xls files using Safari 3 for Windows?

Thanks for reading, and have a great holiday season!