pc blue screened today need some help

hello i have a custom built pc with windows xp os on it and it game me a blue screen today and when it restarted my video card wouldnt post any video on the screen so i reset the biops to its default settings and was able to boot into windows i ran sfc /scannow with my xp cd in cmd prompt to see if my files were ok my question is how do i figure out if its a software related issue causing the blue screen or if its hardware related

What was the STOP error in the BSOD?

i wasnt able to write down the error because the pc restarted as soon as i got the error screen i do how ever remember that before i got the blue screen i had an issue where i was replacing my cpu heatsink and some how the cpu was accidentaly pulled out of the mobo socker while the socket lock lever was down i was able to reseat the cpu into the socket and relock it not sure if this could ber causing my problemsim going to run prime95 tonight to see if i get any errors will report backj on my findings in the mornming

ran prim95 for 6 hours no cpu errors or warning reported

I would think your hardware is good after that run. When it crashed were you using the video card. Like gaming/ streaming anything like that.

last think i did before the blue screen was update my google flash player

heres the info from blue screen view

A problem has been detected and Windows has been shut down to prevent damage
to your computer.

The problem seems to be caused by the following file: win32k.sys

SYSTEM_PTE_MISUSE

If this is the first time you've seen this stop error screen,
restart your computer. If this screen appears again, follow
these steps:

Check to make sure any new hardware or software is properly installed.
If this is a new installation, ask your hardware or software manufacturer
for any Windows updates you might need.

If problems continue, disable or remove any newly installed hardware
or software. Disable BIOS memory options such as caching or shadowing.
If you need to use safe mode to remove or disable components, restart
your computer, press F8 to select Advanced Startup Options, and then
select Safe Mode.

Technical Information:

*** STOP: 0x000000da (0x0000000000000400, 0xfffffadf8be14000, 0x0000000000000400,
0x0000000000000000)

*** win32k.sys - Address 0xfffff97fff13edc8 base at 0xfffff97fff000000 DateStamp
0x521eb30b

Since I noticed that the last thing you did was get an xfire set-up going and this is most likey drivers issue. You should check to see if any additional drivers were installed along with the display driver, like hydravision and HD audio. If so I would start by removing them. If that doesn't help maybe try an older catalyst suite. Which version do you hav instaklled.