Well don't ditch the sound card anyway, I love my audigy 2 ZS. I tried 5.1 surround sound on my onboard and it just doesn't soud nearly the same. So I think that's worth the trade-off to a better case or video card.
There are so many cases it's very hard to choose. You want to pick one that has good airflow, but also matches well in the environment it's going to be in. Of course you also can't spend much so that's another factor.
I don't know if this one looks any good to you.
It comes with a power supply but it's crap so I would just throw it out.
Oh and aspire I have that case and it has great airflow. Better than a lot of cases I'm sure. It has a 92 on the side and top and both of those push a lot of air. With a 120mm on the back you have plenty of exhaust. The top fan works really well because you are exhausting the hot ait that rises out the top. Also if you put the hard drives in the first two slots you can have the front fan blowing under them. But I opted to set the 2 hard drives right in front of the front fan so that the fan is cooling down the hard drives by blowing across them.
And brylax of course if you are adventurous there is always the option of taking a case with a side window that has crappy cooling and modding it a little.
Like drilling a hole in the top for a top fan, stuff like that.