I suggest this for a case. It's $30 after instant savings, promo code, and MIR. The reviews seriously speak for themselves, and I really love it myself.
Amazing airflow if you add a couple fans, the see-through side is a plus, blue LED's, VERY roomy, but not a case that will take up 1/4 of the room. That's all I have for you, but it works as a starting point hopefully!
Uh.... it's a bit on the small side, and doesn't even have USB 2.0 (much less 3.0).
Now, I just want to say that with monitor, OS, keyborad, mouse, and all peripherals that aren't INSIDE (including case) the computer are going to take your budget down to about $400 maximum... monitor ~ $150 (that's really cheap), keyboard + mouse + speakers/headset ~ $50, OS ~ $100. For $400... well... you won't be able to play Starcraft at max settings. It would be incredibly difficult. Now, going below a 1TB HDD saves you a LITTLE bit of money, but it's like $30 less for 500GB... so there's not really much of a financial drawback. I think prices will fall, so we'll say $100 for the HDD. That leaves $300 for CPU, motherboard, video card, RAM, and case. You may be looking at an AMD system, which isn't advisable... at all. AMD is the only thing that would fit your budget, and you may even be looking at APU.
My point is that you should probably buy a console, because you're not anywhere near a gaming build. At this point, it would be cheaper and easier to buy a pre-built $400 build...
Yeah, I'm pretty sure that the best efficiency for a PSU is like 20%-70% of load (ish... I don't remember for sure), so with a 500W you'll be more than fine. I'm sure you could get a 400W and not sweat.