Unless you want to pay someone to redraw your plans in CAD to get the .dxf files, I'm afraid you're stuck with learning CAD and redrawing the plans yourself.
If you already have drafting skills, you can learn CAD. It's much easier if you choose a program that has a user friendly interface such as TurboCAD. Here's a free download of TurboCAD LE (Learning Edition) that will do just fine and doesn't cost a dime!
http://www.al-ki.com/tcad/download.php#TurboCADLE
Good luck!
