I'm sure you've heard that Apple has released a beta of a bootloader than can run WinXP easily. I've seen it in action and while it isn't a true multiboot in the pure sense, it gets the job done.
You need to boot into either OS and select the computer to boot into the other. It is a round about way, but it works.
2014 is going to be a good year. More content, more streamlining. Be a part of history!