Also, I don't think I made it clear that the specs for the p5n-e sli don't just mention a bios upgrade, but one specifically for 45nm support. I surfed around on google and found a couple instances of other folks having the same problem and fixing it by updating their bios. Unfortunately I also found some folks with the same problem that had nothing to do with a cpu upgrade or bios upgrade.
As a side note I believe that neither my keyboard nor mouse turned on like they usually do when the computer boots, which was consistent with other reports of an unupgraded bios no-monitor-turn-on-after-upgrade occurence.
I don't think this is a video card problem, I think my video card was running fine and I remember having similar problems with fooling around with overclocking on my last processor when I pushed the clock too far and the monitor wouldn't even turn on until I reset the cpu settings. I mention this because it supports the possibility of the problem being caused exclusively by the cpu.
Whizkid, please let us know what motherboard you have. Depending on that, I would expect you will either need to reinstall your old cpu to update your bios before going back to your new cpu, or if 45nm isn't supported at all by your motherboard you may need to look for a new motherboard. Let us know though, and I'll give you guys an update when I have a chance to try it myself.