Big Problem with XPS 435mt Dell desktop

So recently i turned my computer off for the first time and i get up the next morning to turn it on and all it does when i hit the power button is the power light just blinks orange once the fans turn once and it doesn't even come on or attempt to startup. I opened up my case and i see a orange light ont he motherboard by the number D27. Also when i try to turn it on the a light on the ATI video card blinks red.

I have an Intel x58 motherboard model number DX58M01. the power supply seems to be fine.

I don't have a warranty anymore it exp in 6/4/10. I don't really know what to do this computer is only like a year and a half old. Do you guys think i need another motehrboard??? Is there anyway to find out myself what exactly is wrong by certain lights etc on the motherboard???

Do you guys most likely think its the motherboard that went out or could it be a simplier or harder problem to fix?? Also how cheap would be a new motherboard for this computer if that is the problem????

Please help i use my computer like everyday and I don't want to have to go buy a new one.

Thanks,

William