It sounds more like a PSU/mobo/BIOS/CPU/memory problem to me. If you put a boot CD into your CD/DVD drive, and select that to be booted first in your BIOS and it skips it, there is definitely something other than your hard drive that is acting funky.
Try resetting your BIOS first.
You can download bootable CD ISOs from the internet that contain basic diagnostics. I'd start from there.
But if you can't even get that to work, disconnect everything else to minimize power consumption and see if you can boot it then.
If that doesn't work you can try getting a new PSU from someplace, like Best Buy, which will take it back if it doesn't solve your problem. Or use the one from your PC that works if it is a more powerful machine and you feel, er, adventurous.
If that doesn't work you have a bad mobo or CPU. Try Newegg, Tiger, or Amazon for a cheap combo. Just keep in mind that if you get a more powerful one than you already have, you might need that new PSU after all.
If you need any more help or suggestions PM me. I rarely access this forum.