$400 is a real stretch if you're looking to build even the most basic of gaming rigs. I spent $900 on mine(noting that if I hadn't had friend build it for me, I would have ended up paying nearly 2 grand for it). Your best bet would be to save up another few hundred and then get a custom build. I'm not sure of computer prices in your area though, so you may have more options than you would up here.
To make a long story short, I don't take any responsibility for anything I post here. It's not news, it's not truth, it's not serious. It's parody. It's satire. It's bitter. It's angsty. Your mother's a *****. You like to jack off dogs. That's right, you heard me. You like to grab that dog by the bone and rub it like a ski pole. Your dad? ***. Your priest? Straight. **** off and let me post. It's not true, it's all in good fun. Now go away.