I upgrade from SP2 to SP3 and it is low on memory before the upgrade.

The problem started yesterday. My computer was doing perfectly fine but then it crashed while running some program. so i had to perform a hard shutdown and restart the comp. the computer was still working fine after that one time but the program was buggy and kept crashing and i had to keep doing the hard shutdown. now times this whole scenario by 30 cause i shut it down nearly that many times from all the crashes. but now my comp wont even last 5 minutes before crashing and this is with the program not even running. i uninstalled it and same thing, i get a crash after 5 minutes. and booting up takes a long time in some parts and even still it doesnt always turn on correctly, it freezes in boot up aswell. even in bios it will freeze. so now im stuck. i tried to reinstall vista and it froze in the middle of reinstallation and then i ran the thing again and finished it up but its still crashing. so im guessing the motherboard got ruined because if it was power supply it would shut down after the crash wouldnt it? and its probably not software cause i completely reset the comp and reinstalled vista and i even tried switching wireless cards and mouse/keyboard. i also ran hp diagnostics tools and it says harddrive memory and cpu passed all the tests.
so pleeeaaase help meee. i cant use this thing without it freezing up every 5 minutes. i actually havnt even been able to get past the initial time setup pages and stuff when you reinstall vista. (using a dif. comp)

when i click on my computer then i right click it and it says properties which tell u how much memory have u used and how much memory is left at the bottom it says disk clean up what does disk clean up do does it make the internet does it remove alll u things?

I have been having sever data corruption issues with the game World of warcraft. i have run every diagnostic software known to me including checkdisk (windows xp sp3) Microsoft’s memory diagnostic tool and seagates hard drive diagnostic tool both windows and bootable CD versions and every diagnostic comes back squeaky Clean and ive even swapped my ram entirely. I have done a full system restore on my computer and i still cant get a stable install which leads me to believe i have a hard drive issue yet it passes every test. so basically my question is as stated above, is it possible for a hard drive to be going bad yet not fail diagnostics. If so is there any way to verify or at least gather further evidence that its the hard drive before i spend money on a new hard drive. (note it appears as if only world of warcraft is currently effected, i suspect its highly complicated file system is more likely to be damaged by a failing hard drive)
i have installed all patches and all blizz will tell me is its a hard drive issue or a ram issue. and it cant be a virus as i JUST reformatted my hard drive. i have also updated every driver in my system. and while its not a data coruption issue limewire shuts down when i attempt to preview a file

I would like all the sites i ever veiwed gone and deleted out of my computer and no way to track them with out hours of work. I’ve gone thorugh and done the delete cookies , files and erase memory but i kno thats not deleting it all, but just forgetting about the sites instead. Let me kno what affect could happen if i did delete all previously viewed sites.

Appreciated!