May be asking for the impossible here....
My younger brother is on an extremely limited budget, but is asking me to come up with a build for him under $400 (crazy I know) that can play games like Black Ops and such on medium-high settings. I built my computer about 2.5 years ago for $650 or so and can still max out games (I don't have a high res monitor though) so maybe it is doable. The thing that helps is when I bought my video card (8800GTX), the seller threw in his extra for about $50. I got it thinking I'd SLI them eventually, but eventually decided against it since my motherboard is only a single slot PCI-E and I don't wanna buy another.
Anyways, so with everything but the graphics card, is there something that you guys can come up with for about $400?