I think mine is already on its way out.
I've been having trouble viewing DVDs on it. I'll sit down and watch a flick, and it'll run fine for about 20 minutes and then it'll freeze. My controller won't respond, nothing. I turn it off, turn it back on, and have the same problem 10-15 minutes later. I called Microsoft and they said it's likely because the system isn't properly ventilated and is overheating, but I've had nights where I played Rainbow Six for 4 hours, and then went and played 2 games of Madden, and haven't had any freezing issues. It only happens on DVD Playback.
They also told me it might be a corrupted save file on my HDD. So tonight when I get home, I'm going to disconnect my HDD and give it a shot. If that fails, I'm gonna take my 360 to gamestop before i get the red light special, keep my HDD and just buy a core system.
If that fails, there's a dude that works with my pops that sells stolen premium 360s for $250.