computer won't power on! help!

I just got my new computer yesterday from ibuypower and now it won't even turn on. what happened is: It worked for about a half an hour and then suddenly powered itself off. now when I attempt to turn on the computer three things happen. The green power indicator LED on the front of the case flashes once very quickly. The case fans begin to turn a couple millimeters. The most noticable thing though is that through my case window I can see that a small amber colored LED on the motherboard turns on after I've flicked the power switch, and it stays on.
my system
mobo:GA-7VRX
1024 MB PC2700 DDR-333 MHZ
athelon 2100+ xp
100 gig hd
400 watt power supply
geforce ti4600
etc.

I have no idea what is going on but it seems like a pretty clear hardware problem since the conmputer was working fine for at least a little while