Seriously just get the 2500K... the ivy bridge CPUs are just sandy bridge with a new coat of paint, nothing special has been upgraded.
Also I would highly recommend a Lian Li case. I got this one:
www.newegg.com/Product/Product.aspx?Item=N82E16811112154
And it's so nice. Extremely solid design, but still light. Has a removable motherboard plate, and some wire management inside, and feels like it has way more space than a mid tower should have. The built-in fans run so quietly and effectively, too. I like the simple black one, but I think they have some transparent and glowy ones.