Here is an I/O shield:
http://lib.store.yahoo.net/lib/directron/mspc9907.jpg . It is the area on the back of your computer where you can attach devices from the outside of the case. The one shown is considered the standard and a similar one comes with most cases like the Ninja - it is removable so that the matching plate that comes with most mobos can pop right in. But it is unlikely that the ports on your Sony's motherboard will match that layout, so you will either have to be able to remove the one from the Sony case and put it in the Ninja or find one that matches your mobo.
. Besides stray RFI getting in and out of your case more easily without it, insects and small animals can also crawl in and out setting up nests, pooping, gnawing on wires, etc. IOW, you don't want that space (or any extraneous space) left open.
Thin metal makes for a flimsy case. It will wobble, warp,panels will bend easily and it will generally be damage-prone in shipping.
A decent case will have toolless drive mounting, add-on card clips (no screws), noise isolators for the hard drives etc. The Ninja has none of those as far as I can tell.
I would suggest saving up for a better case. Immediate gratification often yeilds immediate disappointment...
besides, as you don't seem to understand even the very basic stuff we've been discussing here, then you have considerable more learning to do before tackling your first home-brew. Here's a place to start:
http://www.mechbgon.com see his New Builder's guide.
In any case, for that money you should be able to get an Antec SLK3000-B over there. A much better case than the Ninja where it counts. That's what G-Y was trying to get across, I think.
.bh