Windows 7 Blue Screening

I was having some problems with windows 8 so I got windows 7 and installed it and now after about two hours my computer blue screens consistently and has to got though and run a diagnostic before it can even start. it was having to store to earlier save but Its has gotten to the point where it doesn't do that anymore. OH, and i had to disable windows updates because that stopped my computer from start up as well after it rebooted. any ideas i am think its hardware but i don't know what it could be.

BIOS updated to latest version? Run Memtest86, test the hdd from within a linux distro run off a usb or dvd.

Go further if you like and take the board etc out and do testing with just a single stick of ram, gpu, keyboard. Also if you can borrow a psu off a friend and try out the system with that.