Secunia has rated this as "extremely critical," their most serious vulnerability rating.
The last time this happened was in May, and it took Microsoft 26 days to come up with a patch, during which time there were attacks on various enterprises from systems in China.
This problem affects Word 2000, 2002, and 2003 for Windows, Microsoft Works 2004, 2005, and 2006, Word Viewer 2003, and Word 2004 for Macintosh.
I recommend switching to OpenOffice and Macintosh. If you must use Windows in a business environment, this presents a strong argument for not giving users administrative rights on their own machines (or at least not on the user they login as to use Word) in order to limit what damage can occur from the exploitation of a vulnerability like this.
UPDATE (December 15, 2006): There have now been three such Word vulnerabilities discovered in the last two weeks!