dead hard drives

ive just had 2 hard drive die in 24 hrs. the 1st was an 80 gig 8mb cache wd model. i rebooted the computer and it wasn't recognized, and i hasnt been recognized on any of my 3 computers at home since. i then reinstalled XP on a relatively new 160 gig 8mb cache wd i had. all is right, right? i just started my computer for the day and a burning smell coming from the computer. i turn it off and pull hard drive, its the hard drive stinking, burnt, and totally dead. what the hell? is this a power supply problem? over volting the line and killing them or what? help!!! P4 2.8 on an Asus 865pe chipset