If you have the tools, a case is a case.
You can buy a $20 ATX case and a few fans, strategically cut holes where you want the fans to be so they give the best cooling and then stick the fans on to keep it cold.
If you get the case, even if it is a little over the temps you want you can easily cut a hole or 2 on the side and it will suck a little more air in, or on on top to get the hot air out.
If you aren't sure how to do this, read this thread:
http://www.computerforum.com/144883-cutting-new-fan-hole.html
I highly doubt that it would come to this though, it looks like it shouldn't have any cooling issues. If it does and you are still on stock coolers, that would be why.
There are loads of different heatsinks/fans that you can get for your different components.
For CPU, most are much of a muchness, as yu would expect, a £5 one is pretty much useless compared to standard one, a $200 one will let you seriously overclock and is more for bragging rights.
For GPU, arctic cooling accelero S1 or S2 are your best bets. Alone as passive heat sinks they seriously cool your video card down, you can buy fans that clip onto the heat sink for about $15 or so that will cool it further if you want.
There are alot of NB and SB coolers, same scenario as CPU coolers.
Still though, the case look like cooling should be fine and, unless i am mistaken as i am only going from the picture, the side panel looks like it is just a clip holding it on. If the insides are anything like that easy then you should have no problems with accesability because it would be, like the side panel, tooless.
