Thanks for the replies.
My system was working fine over a month, suddenly it started crashing. I have to reinstall after several crash, since WinXP doesn't start anymore.
When it crashes, it shows the usual blue screen and 'Serious error gibberish' and I can see barely 'memory dump.... Contact your system... The warning message goes away, so I can't read them all, then it restarts.
I'm using Enermax 350w psu, it's possible, but it's not likely the culprit.
My motherboard is A7v266-e, and I didn't see anyone have problem with 3 sticks of ram.
Is it possilbe to use cd-r or cd-rw instead of floppy to run the program?
I didn't bother to install floppy drive.