Question : blue screen of death

i was getting a blue screen a while ago
(because windows update installed a bad driver over my perfectly good driver)
, on start up windows came up with a screen saying it could check why i got a blue screen and it came up with my secondary hard drive driver  serial ATA so i went to device manager and got windows to check for the latest driver it found one and installed it.

system was running fine until today, i got a blue screen when powering off the p.c and i got one when i was in screen saver. now when windows reloads after the blue screen windows doesn't find a problem . what can i do now. thank you 4 helping

i don't have all the specs at hand for the p.c this is all i know:

intel processor dual core 3 ghz
asus mother b
lots of wires  :)

Answer : blue screen of death

MODULE_NAME: wininit        -    CUSTOMER_CRASH_COUNT:  2
DEFAULT_BUCKET_ID:  VISTA_DRIVER_FAULT     -    PROCESS_NAME:  WerFault.exe

not much info on it : it is running a Fault Diagnostic Test in Windows Vista to check for any errors to report back to Microsoft

it can be hard or soft, so i suggest to download ubcd, and run ram and disk tests first.
http://www.ultimatebootcd.com/

if you find nothing, try a repair install :  http://www.bleepingcomputer.com/tutorials/tutorial148.html      

since there is not much info, it can be necessary to save your data and doing a fresh install also, but let's wait before doing that