Not quite sure I understood, you're trying with two monitors, right? Are you using the same video cable for both monitors? It might be that the cable is not working right, there could be some bent pins on it?
But the beeps, memory parity error sounds suspicious. Are the two dimms a matched pair? Or two separate dimms? Have you tried with just one Dimm?
Do you have access to another computer anywhere? You can try the memory in the other computer to see if they cause the other computer to not boot as well. I'd say the memory seems the most likely culprit, although it is possible that your video card is DoA.
Did you buy it in a store, or online? If in a store, you can take it back to them and ask them to test (or plain replace) it.
Creston