I have one of those secretary chairs as well, got it at a yard sale for $5. A few months later the back fell off! I sewed some indutrial strenght velcro together, wrapped around the back and the post, and fixed it. I keep saying I am going to make a cover for it, so my "fix" won't show.
The moral to this story is, get a secretary chair. Oh, maybe the politically correct term would be admin assistant chair.