There are quite few very good pc cases on that web page. The most popular case with gamers is probably the Antec Nine Hundred.
There are mid-tower and full tower cases shown. The actual physical dimensions are different. Do you prefer the smaller mid-tower design or the larger full tower design? Do you have a budget? Do you need a lot of hard drive bays? The ATI Radeon HD 5850 and 5870 are 11 inches long so you will need a case with sufficient room for those cards.
EDIT - CORRECTION - It's the 5870 that is the long card. The 5850 is one inch shorter.
Since your setup is gonna be a high end one and you're gonna be CrossFireX'ing a 5870
video card which is 11 inches long or a 5850 which is almost 10 inches long
You'll need a very roomy high performance well ventilated gaming case
and I highly recommend the Coolermaster's CM Storm Sniper case
which received countless unbiased awards from top reviewers all over the world.
here why: http://www.cmstorm.com/en/products/chassis/sniper/
click on the pagination arrow on the bottom right side on the Awards tab to see all the awards.
and click on the overview and specification tab for more detailed info.
-- Coolermaster designed this gaming case based on the infos they gathered
from pc gamers, enthusiasts and international gaming groups around the world and as a result.
A full featured military themed full tower like Mid tower gaming case and hell yeah all those
pc gamers, enthusiast and gaming groups love it including me and they all say the same thing,
"It is truly an awesome gaming case!".