Thank you all. I have tried my install disk but the grub won't let me boot from it whatever I try. I'll probably just end up reformatting the drive on another computer and try to track down what I can of my old data.
To answer your other questions, yes, I did leave my computer un-secure. It was in my hotel room while I was out playing tourist. After three tours to Iraq where I'd expect the possibility of being hacked, I didn't expect it in my hotel. I also didn't expect that someone who did hack my system would totally destroy my hard drive in the process so I'd know they'd been there. It's easy to freeze my credit so they can't steal much so why leave a trail? Doesn't make sense.