I suspect an awful lot of failures are due to people putting them in tight spaces that have poor ventilation. Air needs to be moving not just inside, but around the box freely to keep it cool inside. Case in point: I have a Dell desktop that has a "variable" cooling fan speed that changes due to heat. The computer was in a closable "cubby hole" with a door on the front. If I closed that door, the fan, even with the computer just idling with a screen saver running, would sound like a Jet. I'd open the door and within 30 seconds, the fan would start to slow and within a minute it would get quiet. I've removed the back and door of the cubby hole and regardless of the strain I put on the computer, the fans never speed up.
Point is this: put your electronics (not just your xbox 360) in a well ventilated area.
I hate trolls.
Systems I currently own: 360, PS3, Wii, DS Lite (2)
Systems I've owned: PS2, PS1, Dreamcast, Saturn, 3DO, Genesis, Gamecube, N64, SNES, NES, GBA, GB, C64, Amiga, Atari 2600 and 5200, Sega Game Gear, Vectrex, Intellivision, Pong. Yes, Pong.
