I'm a new (used) '05 X5 owner as well and will go off warranty in Aug. I hear of these problems on this board and am surprised as well. Previously, I owned a M3, with no major problems (I sold it at 80k).

Also, when I got the car, I bought it from a friend who specializes in BMW, and I asked if I should buy the extended warranty. He said he wouldn't - they don't have many problems. So I'm wondering the same thing you are. Nothing has gone wrong yet, but I'm only in the first 100 miles. Maybe, the people who are trouble free don't visit the site or don't have to post as much.