It's in my Documents folder. Maybe it was being used by Office 2004 for Mac, but I trashed that application already. Is it safe to delete this folder now?
Yes. When you reinstall Office in the future it won't be able to find most previous settings from your old installation.
Correct me if I'm wrong, but isn't that the folder where Office applications save autorecovery data? All my Office 2004 installs have created this folder, I've learned to live with it. However, if it bothers you so much, you can try this hint: http://www.macosxhints.com/article.php?story=20060228051625893
