MAJOR PROBLEM :'( PLEASE PLEASE HELP....?

OMG! Things went horribly wrong this morning! My dad FINALLY agreed to buy a new PC for the office. We originally have a COMPAQ Presario S3100NX desktop PC (Windows XP with an 80GB ultra DMA hard drive), and he replaced it on Friday with a brand new HP Pavilion P6000 desktop PC (Windows 7 with a 750 GB hard drive) thanks to an awesome black Friday deal! Unfortuantely, out of pure excitement, my dad removed the old PC (mind you, without cutting all the files and pasting them onto an external hard drive) and hooked up the new PC in its place. My dad remembered just this morning that he needed to remove all the old data before discarding the old PC. When he came to do so, he plugged the computer into an outlet in the dining room, and that's when things went wrong. He shocked himself and fried the computer! The computer literally lit sparks and made crackling sounds. He said ouch, jumped in surprise, and quickly unhooked it. He then plugged it into a different outlet in the house, and he had the same exact results. Except this time, the computer made louder crackling sounds and then went into pure silence. It's dead now, completely dead. I'm very disappointed because we have everything from the past 8 years on that hard drive. Important files, doents, photos, etc. all lost :'(. Please tell me that it is possible to remove the hard drive from this COMPAQ and put it into the new HP. All we want is to remove everything from the COMPAQ hard drive and put it on either an external hard drive or on the HP hard drive. Please give me some good news, will the new HP PC be able to read the old COMPAQ hard drive? Your time, help, patience, and understanding will be very much appreciated.