Hey I hope your replacement Mobo works out for you. I am highly impressed with how much you are doing with your PC. It definitely sounds like you went through a lot to get it all working right and I can't wait to see your finished project.
I do have a question:
How well does the Dish network via Slingbox work when your internet connection is coming from the Sprint air card? I used to work at a help desk and fixed a lot of connections problems with AT&T air cards. Even with the best reception you couldn't watch a Youtube video. I'm wondering how well your Sprint card handles the data flow and if you get any problems with video endlessly buffering or if playback is smooth.
Also, what data plan do you use with Sprint? I'm curious as to how much once has to pay for that much data going through the Air card.
Good luck with everything!