Oh my God i am going crazy my windows vista keeps crashing

hi everyone
i have a Toshiba Satellite a205-s4577
uhhh

alright
i used spinrite on this its not the hard drive

i changed the ram to a different properly paired 1gb system and a
properly paired 2gb system

nothing works

the system starts in safe mode superfine no problems.
the system starts in regular mode just fine also. HOWEVER after 20
seconds it goes blue screen. memory dump. i went in and started the
system in safe mode it said the system crashed because of some temp
files according to the crash report. it was an xml file and a dll. i
did disk clean up. i restarted. same think after 20 seconds the system
goes blue screen

of course the next thing i tried was start in last known good config.
nothing. this is when i started to mess with the ram. before i got the
damb thing and ripped it a new one. i said maybe i can help myself by
doing msconfig and removing everything from start up. i did it,
prompted me for a restart. i did and still no good.
WHAT THE FUCK IS GOING ON.

don't tell me please don't tell me the mobo is going bad. i hate
changing those things.

ohh while im here.
how do i do a fit boot i did it in xp and it did wonders all the time
i haven't needed it for windows 7 i don't use vista but i imagine
vista and 7 are the same thing and i don't know how to access it.
they system tried to initiate it by itself but that doesn't work.
i mean was is so bad when you put the disk in and typed help and you
read everything you needed and got what you needed done; that we
needed to change this to the current system where we're left without
answers.

thanks