First post here. I was trying to find some tips on how to extend the life of an iMac. I just recently purchased a new iMac and would like to take care of it as much as I can. I was looking for a few tips on.............. 1. Should I always turn off my iMac when I'm not using it OR leave it on and put a sleep timer on it? 2. Is there some kind of diagnostic check program I should use monthly? 3. And what kind of tips do you have that keeps your iMac in tip top performance? Thanks.