If already installed hard disk installed its going to show a blue screen
You cannot put a HDD with Windows on it that was installed on a different computer and expect this computer to boot.
When Windows installs, it takes a snapshot of the hardware, motherboard etc and loads drivers specific to that hardware during the install. If you remove that HDD and place it into a different computer, when the computer starts to load Windows, it will look for the previous hardware not find it and it will BSOD.
could aldo be a faulty stick of RAM
Remove all of the RAM sticks except one. Download the ISO image for Memtest
, Burn it to CD using IMGBurn
both available in my signature or use their Auto Installer for USB Key
. Boot off of the newly created media and run the tests for at least 7 passes each on each stick of RAM separately. If you get any errors (Red) in the bottom pane, that stick is bad and needs to be replaced.
Also, check your XP disc for smudges or hairline scratches.
If the RAM and the CD test good, then Run Seatools
short and long tests on the HDD. If either test fails, the HDD needs to be replaced.