I have three types of arthritis: Reiter's Syndrome, ankylosing spondylitis, and psoriatic arthritis. I started taking Enbrel in Dec 2000 and stopped taking MTX. I should have kept taking MTX because a recent MRI showed significant demineralization of my spine.
Firstly, see if you can get a MRI now as a base-line of your affected joints.
Eight years ago (2004) I had my left MCP joint replaced. Two years ago (2010) a surgeon removed 1/4 inch around my right heel of arthritic "crap." This year I'm planning to have my two TMJ joints replaced.
So ... if you are taking Enbrel AND you notice either old or new joints swelling, get a MRI to compare with your first one. I should have continued with MTX when I started Enbrel (oh well ... )
Meanwhile, keep yourself physically active and maintain a correct posture as much as possible. On the web, go to the Pentagon channel and watch "Fit for Duty." It has lots of helpful exercises you can do.