I like the isk 300 as a small case.
On the build, I see no need to replace the included psu.
I do not like the need for an external dvd drive. That was done to allow a 2tb drive to be installed in the normak dvd drive bay.
A 60gb ssd is too small for the os. 120gb at least.
For video storage, you can buy laptop 2.5" drives as large as 2tb.
The stock intel cooler works well and almost any dual core chip about $100 will have adequate interated graphics for HD movie playback.