Red Ring of Death... I heard you can just return it to microsoft and they'll repair it for you but... from what a few of my friends told me it could take months before you see it again.
got this from microsoft's site.
If you are experiencing this problem, you can submit a console-repair request online. However, before you submit your request, first try the following two steps to verify the problem:
When you turn on the console, look at the light on the power supply. The power supply light should illuminate green even if the three lights on the Ring of Light flash red. If the power supply light is not green, please follow the steps in one of the following Microsoft Knowledge Base articles:
906101 (http://support.microsoft.com/kb/906101/ ) Troubleshooting your Xbox 360 Power Supply when the light is red
906102 (http://support.microsoft.com/kb/906102/ ) Troubleshooting your Xbox 360 Power Supply when the light is orange
906103 (http://support.microsoft.com/kb/906103/ ) Troubleshooting your Xbox 360 Power Supply when the light is not illuminated
Turn off the console. Wait 10 seconds, and then turn on the console again to see whether the problem re-occurs.
But yeah I'd just maybe give a call to the store you bought it from and ask how you can go about replacing it (they probably won't replace it for you if the warranty is up but they might point you to the right direction), or like StresS said, go to the XBOX site.
and here's a really ghetto temporary fix for it: