Here's some cases for you.
This one is latest fad. It's silent for $100 after MI rebate
http://ncix.com/products/index.php?s...actal%20Design
This is a great gamer case with umpteen fans with great ventilation and should accommodate all video cards without having to go to a full tower case. I like it just for the good ventilation. $100
http://ncix.com/products/index.php?s...e=COOLERMASTER
Here's a cheaper version of the same case. $75
http://ncix.com/products/index.php?s...e=COOLERMASTER
This is popular for it's cooling and price and despite it being called a mini tower, it will fit a 5870. $57
http://ncix.com/products/index.php?s...c&promoid=1069
Here's a power supply. It's 750 watts and you would probably be happy with a 650 watt but I didn't see any I could recommend off the top of my head from this sale. Just get a name brand with 80%+ efficiency and you should be good. A 650 watt should be good for two HD 5770s in Xfire if you ever go that route or decide to upgrade your video card. Also look for PSUs with modular connections to cut down on the clutter and look for the number of PCI-e connectors. This one has two 6-pin and two 8-pin connectors, so you should never be limited in video card choices.
http://ncix.com/products/index.php?s...c&promoid=1069
Here's a 700 watt coolermaster for a little less. $76 after MIR.
http://ncix.com/products/index.php?s...R&promoid=1069
and don't forget to price match and check the sales page on NCIX on Wed. evening as that's when the new sale comes out and the good deals are often gone if you wait. I believe ME also comes out with the new deals on Wed.
I'd also suggest the Western Drive Black version Hard Drive, it's faster but a little louder.
http://ncix.com/products/index.php?s...D&promoid=1069