check out the Gallery: Cases thread to see the kind of elaborate madness some of our more aesthetically OCD members build their PCs in, truly amazing.
This is what I'm using atm, my HAF doesn't fit on the desk with the extra monitors.
Case is probably about 5-7 years old, had an AMD 939 socket board in it initially.
Moral of the story: Case is irrelevant as long as your cooling is good, except in the case of aesthetics.
Best cases IMHO: Antec Three-Hundred, HAF-X and most Fractals.