There's nothing at all wrong with using a fanless cooler, if
you know what your doing. If you are building what will be strictly an HTPC, you can underclock a CPU just to the point of being able to process HD video. Then a fanless cooler makes sense. Otherwise, no.
Power supplies - my choice of a PSU for a system with a single video card is the Corsair 550VX:http://www.newegg.com/Product/Product.aspx?Item=N82E16817139004
Two video cards, get the 750TX.