Yep, I agree, only when there's a new os like Tiger I will do a clean install, just to get rid of old preference files and stuff. It really is a wrong idea that you would need to reinstall your os after 6 months. To the contrary, I've noticed that if you regularly do maintenance task (macaroni is a splendid set and forget app) OS X gets more stable with time. The only kernel crashes I've had have always been in the first month of use of a clean install, after that, never... Now I come to think of it, the last application crash I was aware of is even a month ago... It's simply amazing, isn't it?