except maybe for GTA 4, you don't need a GTX 280 graphic card to see this level of detail on a pc, cheaper cards work nifty as well. still to get a computer to perform nicely with the newest game you need to spend quite some money and time upgrading your machine, so I can understand those people who still prefer the consoles. by the way the Xbox 360 is not so much a console like PS3. its hardware is not really much different from the one of a pc, so the comparison should be PC - super custom PC - PS3.. : )

the price of the PS3 is because of its blue ray disc and the better hardware, in particular the Cell Processor that on professional servers costs alone several times more than the PS3 price tag. about games keep in mind that the Xbox360 processor is a General Purpose, so it is basically the same mounted on your pc's while the Cell is a hybrid of 1 general purpose core and 7 specialized cores. so in cross platform games that are developed thinking about pc's architecture the xbox 360 will probably get the best results. PS3 gives his best in games developed thinking about its specific architecture.

it seems to me that the terrain looks more detailed on the xbox 360 while the sky and and distant landscape together with the lights look a bit better on the PS3. but the differences look pretty cosmetic here.