From someone who deals with Macs and PCs working together all the time, MacDrive is the product you want. It works seamlessly.
PCs cannot automatically read mac-formatted disks and need a helper application. There are several out there, but from working with many MacDrive is the one I'd recommend.
You can find it here:
http://www.media4.com/products/macdrive/
Here are a list of alternate solutions for you to look over:
http://www.macwindows.com/disks2.html
If adding a software solution is not possible, you'll need a mac on the network that can send the files to a shared location or can e-mail the file to the PC user.
You may additionally face some issues when you convert the file from the Mac version of Word to the PCversion. Recent versions have done a great job of working cross platform, but this was not always the case. Make sure and check your document's formatting carefully and look for unintended characters, etc.
Good luck, hope this helps!