Fallout 3 freezes

hey if anybody can help that would be great. i just got fallout 3 and installed fine. when i try to play the game if freezes before even loading. i dont know much about computers but if anybody can help that would be great.

i have a pentium 4cpu 2.53 GHz, 1 gig of ram ATI Radeon 9600 series and i think its updated to 8.231.0.0.
when i first installed the game it found what my copmuter could run it at and it put to high. i also tryed puting everything low but it still crashes. i uninstalled the game then reinstalled it and now it gives me the encountered an error and needs to quit. so i tryed the first to patches from 1.0.0.15 then to 1.1.0.35. i haven't tryed the latest patch yet. now with the new patch it gives me the same error with following:
App name: fallout3.exe
app ver: 1.1.0.35
modname: fallout3.exe
mod ver: 1.1.0.35
offset: 0074d515
if there is anything any body can do to help that would be great.
thanks