Tony,
This can happen to any company, just like newswatcher said. I try to run all the parts I sell for 30 days before selling them. That does lower the rate of failure considerably. But I am a specialty computer company. Large companies cannot do this.
When you get the computer, you are doing the 30 day break in at home. If there is a problem with the motherboard, it goes much higher than Dell. It goes to the maker of the motherboard (Dell, Compaq, HP, Gateway, etc. do not actually make any hardware, they just put it together.), or even the chipset maker.
There have been fundamental design flaws been found with Intel and VIA Chipsets. These were highly publicized.
Sorry you had problems with your computer.
Richard
P.S. It is a lot of fun building your own computer. If you find it interesting, you might want to look in to learning how. It is very rewarding.