This is why it's a good idea to use free software or at least check to see the program you're using can save the file in a variety of different formats. This sort of thing is too often overlooked by people which results in them been locked into using one piece of software.
If you just want a PCB design program that can import DXF, you could have a look at target3001 (there is a pad-limited free version to download):
**broken link removed**
From your other post, it is possible to draw arcs within the pcb software itself without need to import from cad, unless it is a more complicated design.
Another possibility is Eagle cad :
It also has a free version (board size limited)