I've just placed a repair order for my first broken 360.  It happened when I started playing COD4.  It froze up on me a couple of times.  Then I got the RRoD a couple of times.   Then on the third start-up, the RRoD was gone and it booted up normally, however, there was a green like tint discoloring going on in the game and on the dashboard.  Powered down and powered back up again and now all I get is horizontal jagged blue lines and has been this way ever since.
My one-year warranty had expired by just three days and they wouldn't extend it.  And since my 360 no longer displays the RRoD, the extended warranty doesn't apply.
Cost: $100.
Their customer service also sucks.