do not by the xbox 3690 if it was made before may of 2007,1 out of 3 is defective or 33% of them. they all have the over heat problem(3 red lights) if they where made before may 2007.so if you are looking to buy a used xbox 360 make shore you ask for the date it was made. i lost 280.00 dollers to find this out.if you have a xbox 360 and it has the 3 red lights go to
http://hackedgadgets.com/2008/05/11/xbox360-rings-of-death-fix-overheat-solder-reflow/
and they will show you how to fix most of them.
beware of used xbox 360 beware