The screen doesn't flash, the white led under the screen does.

I think you are right about the memory. I found that 1 beep = memory problem, but I don't think its the actual memory. I tried 2 different known good sticks in each slot, and it still wouldn't boot. I think there must be a problem with the logic board.

Ah well, that sucks.

Edit: 1 beep = no ram. It thinks there is no ram installed.

http://support.apple.com/kb/HT1547

"in addition to the beeps, on some computers the power LED will flash a corresponding number of times plus one. The LED will repeat the sequence after approximately a 5-second pause. The tones are only played once."

Which is why the led flashes twice.