First - not to make light of your serious situation - but a cracker deleted your files. A hacker did not.
The first thing you need to do is turn the pc off - stop using it. The recovery process will probably have to happen with knoppix or another live cd. While you leave the computer running, you are overwriting the drive space where the unlinked, "removed" files are.
Have a look at the Coroner's Toolkit: http://www.porcupine.org/forensics/tct.html
The tools you may be able to use are unrm and lazarus. I have not used either but I've read about this toolkit.
Unfortunately, with 200GB of data I have serious doubts that you will be able to recover most of it.