Had a problem with my old computer, and my gf's computer. Everything turns on, but the HD doesn't seem 'click over' like when i turn my computer on now, you can hear the HD start up, then the RPMs drop, but with my old computer and my gf's you dont hear this drop.
There is no video (bios doesnt boot up on the monitor). With my old computer, I had onboard video so I switched to that and it worked fine. I don't know if the vid cards are fried or what (put my gf's computer together with spare parts). When I replaced the vid card in my old computer it worked fine, so I assume it's something with the video card.
Also, did you get your parts from newegg? or a retail store? It is possible that it was DOA (dead on arrival)