Good luck Dan...
Sorry I missed the part where you said about trying the onboard graphics. That'll teach me to watch the tube and post at the same time.
I RMA'd my GPU today as well so hopefully both of will have good luck. To me this is the worst feeling when a new build won't even power up. Pretty hard to trouble shoot.
Keep us posted and let us know how you do. I'll have to send back the Mobo/CPU (combo deal guess I'll have to return both) next I guess if the GPU isn't the answer.
Good luck. In the meantime you may want to invest $25 in a spare video card if you build a lot of systems.
Dan