I've known many people with an eMachines that have never had a problem. I had an eMachines before I built my new rig. I had it about 6 years, and although I lost sound and LAN on the motherboard, it ran and still does run fine.
My friend also had an eMachines, which he has dropped down the stairs, basically beat the **** out of it in every way possible, and it still works fine.
My uncle also has an eMachines, two more friends do, and a bunch of people I game with do aswell, all without any problems. From what I can tell, eMachines are not cheap in quality.
Now, do you have a green light on the motherboard when the PSU is on/plugged in? Can you test the PSU on a different computer to verify it still works? You may have toasted the powersupply..
Intel Q9400 | Gigabyte EP45-UD3P | G.Skill 2x2GB DDR2 1000 | XFX HD5870
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