Another I'm building a computer topic
There is a difference. But its not a big difference, that's why I'm using a steel case. They are way cheaper. However, that case you listed is not what I'd call cheap, as it comes with *no PSU*. The case would still work fine. But, now that you've decided steel would be fine, your range of options for affordable cases has opened up tremendously. Also, it says "built-in Hardcano 7", not Volcano 7. I believe this refers to the fan bus/monitoring unit.
You can sometimes buy cases outside of newegg for less, newegg doesn't always have the best price. Don't get me wrong, I love newegg, but I'm not going to pay $20 more just so I can buy a case from them. Anyway, at newegg alone there are other cases to consider. There's the Enermax X- Point series, Aspire "Chieftec" Style cases, and Chieftec cases. I also like Aspire Turbo Case series (with quiet dual fan 420watt PSU), but its aluminum and therefore more expensive - though not by much and it comes with a PSU that would more than suit your needs. I love the HD mounting system a lot. Also, the Scorpio 868 is an inexpensive steel version of the 668, though newegg only carries the 668. The sale at str8buy is over apparently, you could have upgraded the PSU at their site by paying the difference... instead of buying one and then getting rid of the PS. Also, I don't see anything in your plans that would require a sick PSU.