the graphics arent really better, graphics card will make a diff.
but the major diff comes from they had longer time and added things to the xbox version. like the car engine, its not the PC doesnt look as good, its that they just didnt add it in there.
On that site posted. the PC version is at a low res. AA turned off, or low, and each pic is zoomed out. That much is obvious from the start. Finding your own pics that are somewhat the same as each other, and the outcome is somewhat differnt.
But PC has downloadable mods. so

on ps2 and xbox versions. hehe
but tis good game. anyone who hasnt played it should defently pick it up