Lately I've been getting attachments of all sorts (from all sorts of people) download to entourage download themselves as winmail.dat. Does anyone have any idea how to solve this problem?
This is a problem at the sender's end. They are sending mail in rich text format, assuming that a Windows Email user is at the other end, and its sending the mail bundled into a TNEF format - which the Mac programs cannot read. Contact them and ask them to change the preferences on your entry in their address book to "plain text"
There's a little program called TNEF's Enough that can extract the info