Quote Originally Posted by Sceptile_Master
So am I right in saying Microsoft office uses the WMF format for embedding images into the documents it produces.
No, a large proportion of Microsoft Office programs use either bitmaps or the original file type for embedding images.

Quote Originally Posted by Sceptile_Master
Does that mean this problem is most common in sites produced in such programs as word and publisher?
No, only specially-crafted WMF files contain the exploit. Web sites built using Word or Publisher would only carry the exploit if their authors embedded a specially-crafted WMF file in a page of the site. Speaking of which, any webmaster who uses Word or Publisher to create a web site should be immediately sterilised.