There are also 2 service packs available from MS to load on the client. One for Office and one for Outlook2000. When both are loaded, all dangerous attachments are present, but unavailable. If you really need them you can go in through OWA and download the file to your hard drive.
There are about 20 file types that are blocked. (Exe, bat, vbs, js, shs, ...) I have not yet figured out how to edit the list of what is blocked.
Dan