So I tried out the stair machine at the gym this weekend.  Eventhough I haven't been to the gym in two weeks I found that I could comfortably do 50 stairs per minute.  I ended up doing about 10 minutes worth of stair climbing (before going back to the elliptical).  In those 10 minutes I did 40 stories, so I'm pretty confident that I'll be able to handle the real climb (80 stories) even if I don't workout from now until then, which is unlikely.