What u r watching is called BSOD (Blue screen of death)
Possible reasons:-
1>Bad sector in the OS partition
2>Loose cables
3>Faulty RAM (Highly possible)
4>Driver mismatch (any driver, s/w u have installed recently is having issue with ur PC)
Can u boot into SafeMode of XP?
If yes, un-install any s/w u've recently installed. Also run a chkdsk on ur OS drive.
If u can't even boot into safemode, check ur data cable connection.
Then check ur RAM. Try the RAm module(s) in different slots.
Report back ur results.