First I want to say that it sounds like its a good thing that your getting out of where you where. I would say fight for the money you earned but I myself got screwed in a similar fashion. My last job was as a director of technology for a school district, to make a long story short they started making cuts and I was one of them. When I asked about my last paycheck I was told that they "adjusted" my salary based on my termination date...wtf ever!

I wish you luck in your interviews! I actually had an interview Monday myself! Hoping I hear back for a second but if I don't I'm in a stable place now.