Question on upgrading case

Any atx full tower case can accomodate you pc components. Just look for "atx" in the title or description.

The Antec Twelve Hundred would be an excellent example of an atx full tower case:

http://www.newegg.com/Product/Product.aspx?Item=N82E16811129043

You'll notice that in the header at the top the case is identified as "ATX". It's one of those classic cases that one buy and keep for a very long time. It's also a very popular full tower case with gamers.