honestly, do you really need an i5 for this task? you could save a lot of money and make your life a whole lot easier if you go with a socket 775 platform..
something like this?
http://www.newegg.com/Product/Product.a ... -_-Product
it's got onboard graphics with DVI and HDMI outputs. You could pickup a nice C2D processor to pop in there, and it's going to be more than powerful enough for your purposes.
http://www.newegg.com/Product/Product.a ... 6819115037
Yes, I use this processor. And the reson I reccomend it if you go with the Zotac board is it's much lower power than an i5 750. You really don't need 4 cores for a media system..by shoving it all in a small case like the antec isk-300, you're asking for trouble if your components put out too much heat.
Now, if you REALLY have your heart set on the i5 750, I wouldn't go any smaller than a mATX board in a mATX case. For this, I personally like this case a lot:
http://www.newegg.com/Product/Product.a ... 6811129054
Very suitable for a bookshelf, and won't cause your CPU to burn up.