I had a similar problem. 2 red rings came up after playing Resident Evil 5 for 30 minutes. Anytime I tried to play after that, the box would just shut down after a few minutes regardless of just sitting in the desktop or actually playing a game. I take it that Resident Evil 5 was just that awesome that it killed it.
Seriously though, this happened Friday (July 10th) and I shipped it Wednesday (July 15th) after bitching to customer service, supervisors, and e-mailing the CEO. Basically, they said there was nothing they could do until I paid for the repair. It was $100 as the only things covered under the 3 year warranty are 3 red lights and an E74 message, NOT 2 red lights.
So, you might have to pay $100 to get your console back if they actually do check it and see you don't have the 3 red lights. They will just keep it until you pay. I'm sure there are a lot of people that try and pull that stunt.
Regardless, I find it better to actually pay microsoft in this instance (and trust me, I really hate them right now for making a faulty product) because once they repair it, they extend the warranty a year and you'll still have 3 years on the E74 and 3 red lights problem. It is $30 a year after that to cover everything. I took good care of my console so I was pissed when this happened and fully believe that yes, there will come a time in a year or so when it happens again 'cause there was no reason why that thing should have gotten 2 red lights except for the fact that Microsoft was negligent in making those things. Besides, we seem to have been in the same boat because I got my console around Christmas of 2007 and the warranty expired Christmas of 2008.
Luckily, after talking to a rep today, I am getting some free shit out of it as if you bitch enough, they give you a list of things to choose from including games and accessories. Sure, I wish Blaz Blue was on said list, but alas, I am sure it will be something like Perfect Dark Zero and microsoft points....microsoft points for Turtles in Time and Marvel vs. Capcom 2!
Hope this helps. This was my experience so far. I won't get the console back for another 2 weeks.