Some people dont mind emachines (me), and some dont like them at all, but i would rather have an emachine than a Dell with a proprietary mobo and ps!!
Anyway, a suggestion, you chould start your own thread.
On the other hand, you could follow all or at least most of the suggestions in this thread to work on your machine.
It may very well be your power supply but it may not be.
Unplug this pc from the wall and hold the power supply button in for a full minute. This discharges any power left in the motherboard and sometimes does the trick.
Here's other things to try:
try a different ps (you should be able to beg, borrow or steal an older used power supply to swap with the one you have, just to test it and bring it back )
re-set bios
re-seat cpu and make sure fan connector is on the right header
check all cables, connectors, etc.
remove all ram except one stick (except rdram)
make sure all pci, agp cards are installed properly, they can get loose.
If that fails take the mobo out of the case and only have video, 1 stick ram, cpu\hs\fan, keyboard, mouse, one master hard drive, floppy or cdrom. Try and get it to boot like that. If it wont boot that way then unhook the floppy, cdrom (dvd), hard drives and try again.
Take out ram and clean gold contacts with tissue paper and re-seat.