You should ALWAYS back up a long post before you try to post it. I've written up too many long threads and lost them because I didn't back them up(for instance, I backed up the "The2" thread before I posted it, because it took me probably half an hour to an hour to find and quote all of those posts.)

I even have the "Remember me" box checked, but I still back up long posts. You never know what might happen, Zelaron could be temporarily down and you get a 404 message and lose your post, your internet might die and you try to post only to get an error page.