What are you going to be using this system for? Gaming i assume?
If you are only at 1920x1200ish get 1 GTX275 and get a second one later on if one wont do it for you, the GTX285 is way more expensive than it should be for being a slightly higher clocked 275, and the OC'ed ones are super expensive http://www.newegg.com/Product/Product.aspx?Item=N82E168...
What case are you getting that you need to get 5 extra fans?
Also since your question is "Does it make sense?" I thought I would point out that it doesn't make sense to pay $350 for that motherboard. This one suits your needs perfectly and is $100 cheaper. And of course I agree with hunter that a single 275 will be fine as well.