Hi,
First off go for the Antec case - they are much roomier and provide much better cooling.
Get another MOBO, the one that you have selected is expensive and not any better than others.
SLI is a waste of time spend the money on a single GPU, that performs much better and costs around the same as an SLI setup.
Go the QUAD CPU route as they cost the same and they are more futureproof than dual, and if you wanted they can be OC'ed better.
I have added a link to a previous thread http://extremetechsupport.com/forum/pc-building-and-hardware-reviews/3957-building-new-computer-need-advice.html to expalin in more detail the past 'issues' with some setups.