by the way - this is a great hack. My attachments table had grown to over 400 mb alone. I never liked the idea of keeping binary data (blobs) in a sql server table.
I have also created my own hack to use mogrify to automatically reduce the size of uploaded images and avatars on my forum and my users love my site. They have no idea about how their attachments are stored but it's pleasing to me to have them as separate files instead of cluttering up my database.