What are you trying to do exactly?
The files created in DW are not platform specific (they're just .html, .css, .js etc) but the program itself is when it's one of the old perpetual license/disk versions.
Adobe doesn't allow platform swapping for anything but current versions, however the current version (DWCC 2014) isn't really platform specific anymore since you can have it installed on two machines, regardless of platform. So, basically, cross-grading/platform swapping isn't allowed anymore.