office talk

I don't have a good photo of my office set-up, so I can't show you just how non-ergonomic my office really is. I spend way too much time working at my computer and I've decided that I've got to start setting things up properly. After reading this article, I'll need to place a shelf under my computer so the monitor is at eye-level and I really, really need a good office chair. Ideally, it wouldn't be too ugly or too expensive. Any good ideas where to get a great (ie. comfortable) office chair?