Actually I'm changing my mind after re-reading. If it comes up with
Primary drive 0 not found
Primary drive 1 not found
Secondary drive 0 not found
Secondary drive 1 not found
strike F1 to retry boot, F2 for setup utility.
It's not finding any of your devices, this sounds more like a Motherboard issue IMO. Was the RAM you recently installed compatible with your motherboard? Does your motherboard accept 4GB of RAM? The RAM may or may not be related to the problem your having, I would try to reinstall your old RAM and see if this changes anything, just for a shot in the dark. If not I think its the board, I don't see how all of your drives would crash at once, it should at least still see the CDROM drive if it was just a dead HD.