Unknown cause to CoD4 BSODs

Keep having blue screen errors of death..... very annoying, sometimes it blames the drivers sometimes it can't find an error report because that's corrupted / errored itself, i've followed the CoD4 general FAQ to erroring and tried those options but to no avail.... although i have all of the newest drivers AFAIK... one thing that i did notice though, was that looking at my profile.xml it reads my very old card Radeon X1950 rather than my HD3870
It points out a few options what to do (all which i've tried + failed) except system restore which won't do jack all...

PC Specs: Pentium D 2.8, 2GB Ram, Radeon EAH3870, ASRock Conroexfire eSATA2, Win XP SP3, 700W (checked with a wattage thing and it says i'm at less than 400W if i inputted the details correctly anyways) i run it at 1280*1024resolution seem as i only have a 19" with the majority of settings on low/medium

Sometimes it runs perfectly like i can get in a server, 80-125(capped) frames... the bombers don't help which usually cause the video to freeze up then the computer makes a horrible noise then resets, sometimes it just soft-restarts itself without the horrible noise when i'm trying to change settings like 75 -> 60Hz or any sound or any other option...
Any ideas? im pretty sure i have the latest drivers for everything

Other information: Warcraft works fine without a hitch... sometimes in BT fighting illidan the fps drops to like 3 while those darn flame demon things are out but yeah

Crysis, not played it for a while but it worked fine - i could try that out and BF2142 for further checks to see if it's only with CoD4 as WoW doesn't use as much resources as the other games i have it seems (apart from dungeon keeper 2 which is super old lol...)

If i missed out any important information which you may need just ask and i'll get back to you asap.