I'm really enjoying my new 27" i7 iMac. It has a quiet Western Digital hard drive, a uniform-enough screen and no strange noises (unless it's really hot and I put my ear right up to the back vent.) The second day I owned it, I noticed a speck of dust trapped between the LCD and backlight and now I'm being neurotic about it. If it was there on the first day, I didn't notice it. I don't want to exchange it since it's such a minor thing to exchange an otherwise incredible machine for, and there's no guarantee that replacement wouldn't have other, worse defects. I tried tapping on the screen with my knuckle around the affected area. No movement. I then had the idea of using compressed air, carefully directing the red tube into the vent and through one of the round holes into the case and giving it a few quick puffs. Of course, I wanted to see if anyone here had done this first. I don't want to stir up more dust in there either. Any ideas?