How many ppl here use a fan? I use one i got from play.com by Nyko.
Iv heard that they can be bad for the 360 but surely they must be good for it too.

 

They draw too much power from the port on the back of the cosole, and can cause it to burn out. Also, they can cause power fluctuations which either make the 360 crash, or make it report hard drive failures etc...

The disadvantages outweigh the advantages. If your console is well ventillated, you shouldn't need one anyway. If you must have one, I'd get the cooler king, which draws power from the usb port instead of directly from the power socket. It's a lot safer...